What a great explanation and thank you for putting it in a way thats easy to understand, youve gained a subscriber. I'm having a hard start problem with my lb7, 10k on new injectors, airdog, cp3 and other supporting mods including fuel filter delete. When truck sits over night it starts absolutely perfect, after I shut it off I can immediately start it with no problem, if it starts to sit between 1/2 to approximately 2 hours it turns over a lot and sometimes won't start without starting fluid (I know! 😂) and if it does start it it starts at a low rpm and then revs up to normal. At the 3ish+ hours it starts normal again. No noticeable fuel leaks but it does have the original factory fuel lines from the tank. Any suggestions? I was thinking an air leak but didn't want to throw money at it guessing
Spent days researching why fuel is being pumped back to tank and never creating pressure! Finally the best breakdown of a system without u tube nonsense Thankyou for making this video I'm finally clear where my problems may be.
Tony, thank you so much for an excellent presentation. I have been wanting to add a lift pump to my 2005 GMC Sierra because I've seen lots of videos on you tube explaining the advantages of this. However, I was still hesitant because I didn't know exactly how the entire Duramax fuel system functioned. Thanks to you I now feel confident that adding a lift pump will be beneficial to my Duramax. Love your channel and keep the great videos coming.
Thanks Tony for such a clear, concise video explaining how the early Duramax fuel system functions. I have subscribed to your channel and plan to see all of them. Thanks again!
@@dieseltalkwithtonysalas8725 Tony I need help with my lly crank no start all of a sudden happened one time before and it was my ficm so I replaced it again thinking it was the same thing and no start any suggestions
Tony, thanks much for the great explanation! Just replaced the filter assembly after my LMM left me stranded in a parking lot. Realized I lost the prime due to failing seals in the assembly. Your explanation helped fill in the back story. Love the comment about idling when sitting there filling up - not sure why folks think they still have a 70's era diesel.
I have an LMM and experienced the same problem as you after a long drive from LA to Phoenix pulling our RV. I was able to re-prime with the hand primer to get it started and its been fine since. Nonetheless, I just ordered the fuel filter housing and am going to replace upon arrival. It appears to be an easy job, but any pointers?
I am having problems with my 2003 duramax 6.6 L not starting. It is a prime problem, but with your video. I have the confidence to fix the problem. Great information about the fuel system. Thank You
Maaan!! I wish there was a ❤ button!! I’m new to your channel Tony and thank you for your wisdom on this topic! I own a 04 GMC with a LB7. It has very low mileage and is in excellent condition. I’ve had struggled with electrical gremlin and now having fuel issues too. I’m extremely happy I finally found your channel! 🙏🏻❤️
Sorry didnt respond sooner. With LB7 using a good fuel additive goes a long way. There are some great upgrades like the banks big head and raise the boost from 20 to 27 psi. No prgramming needed and improves fuel economy
Stuck duramax with crank no start, 185k on a 04. I am not a mechanic nor want to be but I guess forced in this case. Your video helped me understand the fuel system. Thank you. Fuel cap first, then the filter head, both oem from the factory.
@@dieseltalkwithtonysalas8725 I have the 2004.5 truck with the lly. Tried the pump and crank process yesterday. The only thing that hasn't been replaced on this truck's fuel system is the injectors.
With regards to the fuel cooler.... hot diesel is of course "bigger" in volume. This reduces power! We were testing the output power of an 850KW generator, but couldn't get full power from it. I leaned on the fuel tank and noticed it was screaming hot. Seems the guys had just dumped a couple of jerry cans in there since it was just a quick test. As the return fuel dumped in, it just kept getting the fuel hotter and hotter! Output was down about 15% at the end. Not a small amount at that level.
I appreciate your u tube post. It was very educational for me. My truck died after a minute of running. I went to an online auto parts store and paid for a full housing like you mentioned it may be the way to go. Got the housing and installed. Sadly enough the primer pump leaked. Returned for a refund then decided just to go to the rebuilt kit. Another week later it arrived and I installed and yet again that primer plunger leaked. Both came from the same manufacturer. As funny as it sounds I put back my original seals on the primer housing and it kept the system vacuumed. Whether the other 3 o rings were at fault remains a mystery. For the price canadian 242 vs 27 I'd go with the rebuild kit. But the manufacturer that I dealt with and is very common failed to provide quality replacement and 3 weeks of truck sitting and trying to work in sub zero temp
@@BettyFowler-e3j there needs to be a vacuum in the fuel line on the duramax in order for fuel to get to the injectors. That vacuum comes from priming the fuel filter. The primer knob at the top should offer a bit of resistance when you push it down. If it's easy you don't have a vacuum. The o rings would need to be replaced in it and you can buy a ring kit and replace them very easily.
Hello Tony, thanks so much for the great presentation! Nice diagrams and clear delivery! I am in the midst of replacing injectors on a 2004 LB7 with only 94k miles and there are two things I would really appreciate expert advice on: 1) On each side, the rear injectors had a load of gritty crud at the inlets, and corrosion outside the metal/metal sealing interface. Fairly clean at the front injectors and no corrosion, but both symptoms progressively worse towards the rear. Do you know what this would be from and how to protect against it? 2) I would like to leak test the installed return lines. I have seen a nice video of replacing the block banjo with a special one that allows the line and 4 injector return connections to be tested, and this does test all the line welds, but I don't have one and I would like to test the block connection too. The return line from the engine has the CP3 and the regulator on it ..... Would a vacuum or a pressure test be feasible on the line without leaking through or damaging those? Thanks so much for your consideration of these things.
It is common to find grit on the inlet of the fuel injectors. How to reduce that? Fuel filters! I push for a supplement fuel filter to add. Second, it is easier to buy a hand held vacuum pump from a local parts store. Vacuum test the return , may have to get creative with the plumbing but I have never had to on the LB7 s. Make sure you replace the banjo gaskets and torque to spec
Hello Tony, this is very informative, thank-you. I want to get a new fuel cap which has the pressure relief features built into the cap that you described to be so important. Would you please recommend a source for me to purchase that cap for my 2004.5 Chevrolet K2500HD Duramax 6.6L (LLY) truck? I have check the GM replacement parts, and don't see any that include the specs for the cap describing the pressure relief that you referred to.. Thank-you in advance, Bryan
We have a suspected air in fuel problem. The fllter head has been replaced with new OEM and still will kill once in a while then run smooth again. I recommended to my son to put a clear hose on the fuel return hopefully under the hood and run the clear line up under his windshield wiper to monitor while driving. Is this the easiest way to diagnose air in fuel? I'm thinking it HAS to be the issue but nothing is for sure so it'd be nice to confirm.
I still don’t trust filter head I apply a vacuum using a hand held vacuum pump. This is done with a liquid separator So the vacuum pump doesn’t suck fuel. This is done at the outlet line of the fuel filter housing. You apply about 12 inches of vacuum and see if it holds. If it doesn’t the filter head is leaking. If that’s ok, how do you know it’s fuel related? Do u have a scan tool or handheld to monitor fuel rail pressure?
this is an awesome training video definitely have shared with my technicians. Is there any way to bother you for the slides to utilize with the newer techs as we develop their skills to better their career?
I’m in class .. learning. Have a 2093 1 ton Silverado..lost power and white smoke came out. Oil looks okay. No leaking . I also found out my fuel filter wasn’t put on right. So is leaking fuel -and won’t start. Though I see this video to know more about my fuel system
Grrreat... after i bought TWO new green locking caps, aftermarket : /. Better go check them now, Really appreciate the heads-up! (is there any way to tell just by looking at the cap?) [Btw, used to work at a truck stop... can't Stand little boys who leave their diesels running at every store and fill up. Even in the cold, once it's up to temp, it just shows you're not smart)~ thx
Thanks for the comment! If high the first question is the truck modified with aftermarket lift pump? If not it could be an issue with the MPROP or fuel pressure regulator on the injection pump. But need to verify power to the connector and ensure there is no codes set for it.
@@dieseltalkwithtonysalas8725 Thanks for the response! The truck does not have a lift pump in it yet, is the MPROP the sensor on the passenger side fuel rail? The only code is the P0089
Tony...Excellent presentation and keen knowledge on your part. I have question. Below you advise changing fuel filter every other oil change or 20k miles. My 16 LML goes 25k-40k miles before I have to change it. It also trips a change fuel filter light at about 14 in Hg I believe. Now on my LBZ, I installed a vac gauge at bleeder port on fuel filter head and monitor that before I change it. When it gets close to 8 in Hg, I change it. Also, I work in the filtration biz, and typically with single media filtration, the greater the differential pressure(vacuum in the case of a duramax fuel delivery arrangement), the more efficient your filtration will be until a)media breakthrough or b) a fully loaded media. My question is at how many inches of Hg should a stock filter be changed?
First of all I say change filter every other oil change which is every 4k oil change which makes it every 8-9k. If you are seeing 14 inches.. we’ll that s high Spec from GM states no more than 10 inches My spec is 8. However! You have a LML. Those readings will hurt a CP4 pump. But then again I recommend a lifer pump on those models. Thanks for the comment!
@@dieseltalkwithtonysalas8725 It's been there about a month now, Very happy with it. I also bypassed and removed the engine bay fuel filter since the Air Dog has water separation and a filter.
Excellent Tony, Thank for the info, Question my 04 mid year Duramax LLY has a fuel controller you stated that the lly dint have one. did chevy used it on some then discontinue use? Thanks
You mean the FICM. The 04-05 have one but the 06-07 LLY DOES NOT. Hope it helps! Thanks for the comment! More videos coming soon been slammed. Got to Denver tomorrow to teach at a shop!
Tony I just want you to know that the fuel system you're talking about here does not suck the fuel from the tank. What is happening is the pressure in the supply line is being reduced allowing atmospheric pressure to push fuel through the system.
@@MylesSpengler don’t split hairs Negative pressure on one side creates a low pressure under atmospheric absolute pressure. In our trade anything under atmospheric is considered a vacuum. This why we measure the suction in inches of mercury. Suction is created to pull fuel from the tank to the injection pump Atmospheric on one side in the tank which needs to be vented and low pressure suction on the other. Geeez
New subscriber!! Loved the video! Just bought a '05 LLY with 376,000 miles with some issues,but nothing I can not fix myself with some research. I ha e a edge cts3 monitor and my e.c.t is showing -40 and the engine idles at 850 rpm so the ecm is making the engine rich to compensate. I have Ohms out the ect sensor and is reading zero,meaning the sensor is bad,I believe replacing the sensor will correct my problem? Your thoughts sir?!?!?!?
-40 degrees usually means an open in the circuit or short. ECT sensor should not have 0 ohms. It should have resistance. I would have to look it up what it should be since it varies with temperature. Check reference voltage to sensor, with key on, measure voltage across the tow terminals of the sensor, this is with the sensor disconnected, obviously should read 5 volts. Since the ECM thinks it is cold, it will idle up.
Hey Tony, thanks so much for the video man. you’re a godsend. you should have a diesel course for sale. i’m having a problem where my new fass pump is losing prime and my truck will die whilst driving. the rail pressure goes crazy and rpm is bouncing at idle. if i prime all the air it drives fine for a week maybe two and then it starts to act up again. having a sump installed on the bottom of the tank as well as a hp gauge for the rail. do you have any recommendations or anything? i’ve been stumped for a year on the issue and have gotten the cp3 and injectors rebuilt. entire system is new.
With the complaint you have I take a look at the pick up in the tank. If the fuel levels runs low ti can lose prime on a high speed turn. I would first run a line to a 5 gallon tank and see if the vehicle loses prime. If not then need to check filter housing
Thanks for the information video but I have a couple qestions for you if you have some time. I have an lb7 Duramax completely stock replaced the injectors 10k miles ago has 315k now boshe reman injectors new hard-lines new seals o rings thermostat the whole 9 now I have fuel in my oil took the truck apart tore of the driver side cover and started it to look for fuel leak from the return line or possibly cracked injector. Nothing obvious so today I took appart the other side and did the same this time taking off the filter and adding uv due to it now I can’t seem to get the filter to prime I didn’t disconnect the Fcim banjos tried bleeding it from the housing and the hall valve nothing hear air and some times fuel but it won’t get hard. When I started the other driver side sat and ran fine no issues but the primer didn’t get hard either just bled some air out but that was without taking off filter or any rubber lines. Also had surging at low idle coming to a stop never a huge lose in power just the falling on its face for a second then kicking in when I was taking off like you had said in the end with air bubbles. I don’t know how to get this thing started again coild it lose prime through cp3? What tool would i need to test filter housing or could I make it? Thanks for your time I really appreciate it.
Ok a quick answer on one thing before I knock out .. long day One to test filter housing you apply vacuum on the outlet line of the housing for a leak. Should hold vacuum. Second, to find leak on high pressure side valve covers have to be removed. Disconnect regulator at the CP3 pump and IGN relay at the fuse box on the drivers side engine compartment. Have someone crank engine over while you use a colored led light to find a leak. The reason why we disconnect the regulator on CP3 is to go to max pressure and find leak. Reason why IGN relay is removed is it cuts power to FICM to engine won’t start. Let me know… Tony
Just found your channel and learned a few things from this video. I replaced my cap on my LB7 with a locking one, how can I tell if it has the vent and relief valves.
Tony, I have a question... reliability aside, might it be better to fit a CP4 onto an older engine? Higher psi is obviously better if the injectors can handle it, no? (btw... great explanation on the greater pumping volume of the CP4, ...But just for the record, the plungers are moving twice as much as the CP3, so might they wear out faster....?) thnk you
The CP3 has done a great job. It’s isn’t surprising to see that pump go over 500K miles. CP4 is a good pump but the low lift pump pressure and air can destroy it. As time as come by many are realizing the pump isn’t that bad as thought. Thanks for the comment!
@@georgehofgren6123 leave that CP3 in there! It’s a good pump! Keep fuel filter changed every other oil change. Use a good fuel additive once in a while.
Just found this video. Got a low fuel rail pressure code today and it went into limp mode an hr from home. Limped it to a friends house and immediately went to the filter head to check prime and no prime. Found no leaks. Replaced the fuel rail pressure relief valve and the filter head. Still had the problem. So I took the return line off the cooler and nothing came out. But as soon as I primed the the system it started flowing out pretty good. After watching this I'm leaning toward injectors. Your thoughts would be greatly appreciated as I'm about to start throwing more money at this pig. I don't want to do injectors right now bc of money and time it will be down for longer than I can afford. I was wondering if an aftermarket lift pump would solve this. Truck has 200k miles on it and bone stock everything.
I loved this video, but I have a question. So this fuel pump has a mark to put it in timing, but I'm a little confused because the olds version of course needed timing because it worked mechanicly ,but in this case the system is controlled by sensor-modules-injectors means electronically and the pump function is generate pressure only. Why does it have a timing mark?
Happy Thanksgiving! This pump simply sucks and pumps! There is no timing to be set. However! We have seen harmonics from the pump cause what we call an off idle diesel knock sound. Doesn’t affect performance of the engine but it’s annoying. To fix this we remove the pump and move the gear 30 degrees. We reinstall. I can explain further this but it’s a big explanation! So to be clear there is no timing mark or procedure to time the pump on LB7 to LMM. Later model LML, LGH Duramax do have a timing mark. RAM Cummins 6.7L due have a timing number etched on the CP3 shaft to set at 9 o clock . Thanks for commenting!
I bought a 2004 duramax truck about a year ago with 129,000 miles. I only use it for firewood, gravel, and suchlike heavy duty chores. Otherwise, I dive my 4runner or Rav4 Hybrid that I don't need to worry about getting stranded in. Long story short, I did essential upgrades to the truck (intake throat, lift pump, and trans cooler) and drove it only about 1,000 miles since I bought it. During that year, it stalled on with no warnings twice. First time, it started after 10-15 mins, the second time I had to disconnect batteries for a few minutes, and then it started. There are no fuel leaks. Yes, I despise gm (and suchlike) dearly but what the hell?!? Any ideas? Thank you in advance.
@@dieseltalkwithtonysalas8725 It cranks fine, yes, I do have a professional Autel scanner. There was a code P0089 - Fuel pressure regulator performance caused by too high pressure from the lift pump. The first time it stalled before I installed the pump so I don't think it's related, and there were no codes.
is the CP3 pump the same pump no changes for all of these years ? is it just the fuel pressure regulator that has changed with the different model years?
LLY coughs on acceleration.. Change the fuel filter still same problem.. Fuel gauge stop working Could this be the problem? Should I add l lift pump while at it? Awesome Detail on your video. Thanks!!
Generally when a diesel coughs as you state it is not pressure related. It is usually a cylinder misfire or sensor issue from my experience. This is where I need to check all cylinders are operating and check fuel balancing rates.
Thank you Tony for this video. Can you tell me, when i pump fuel from hand primer to cp3, have the cp3 to hold this pressure? Because i noticed, with engine off, fuel coming out in the return line to tank when i push the primer, the pressure is away after 1 minute, i can pump again. My engine shut of after 10 Seconds, so i think high pressure side is good, no codes. 2003 lb7
@@pascalkobler1020 Good morning, when you pump on the primer pump towards the CP3, you also push fuel into the crankcase of the CP3 which also lubricates the internals of the pump. This lube fuel is regulated by the cascade valve on the CP3. So it is normal to see some fuel coming out of the return of the pump. In diagnosis GM has a test you perform with the fuel pressure gauge. You pump the primer pump to 10 Psi and watch the rate of drop on the gauge. If it drops to 0 psi within a minute, replace the CP3 because the cascade valve is stuck open. Obviously this is done with engine off. Hope that helps , getting up, make coffee
@@dieseltalkwithtonysalas8725 thank you for this clear information! If you come to Switzerland, i will invite you for coffee. Test gauge is ordered, so i can check that. Thank you!
Great video! I installed reman bosch injectors on my lb7 and after about 200 miles of it driving fine it started blowing a large amount of white smoke under a load and feels like it's missing. I have a decent video of it but I'm not sure how to attach it. I had a code for maf sensor so I replaced that with the issue still being present. No loss of coolant or coolant smell from the exhaust. The only odd reading I'm seeing is mm³ of flow is almost double what's expected when this happens. Balance rates are all 0.0-0.1. Any ideas of where I should be looking?
Doubt it’s the MAF sensor. White smoke is un burnt fuel. Sounds like injector issue. When looking at balancing rates? Can u see which injector is going above 4 mm3?
I am studying diesel to provide new means for myself an because I’ve always done gas my whole life I purchased the book from my community college an read it every day , I am not a student but that by no means is limiting me to studying an learning this. I wanted to ask you. Concerning this system how do you actually test into the system to check for suction. Do they sell kits or is there a port that you can place a gauge that tests vacuum? Also concerning the internal gear driven pump. Can those be replaced or the HPFP be rebuilt to save funds for those that have more time on there hands including the injectors. If the ball inside the injectors is the weak point for older models does that mean they can be disassembled and replaced or the components be repaired to correct leakage? Do cp3 pumps needs to be timed or is that only for the cp4 pumps? An how does the computer recognize if the pump is incorrectly installed does it throw a code? or is there a way you can monitor it with a scanner to see if it’s not timed properly? there are so many questions I have but I’m extremely eager to learn.
Since I cant highlight replies, I can make them in CAPS. 1 Concerning this system how do you actually test into the system to check for suction. Do they sell kits or is there a port that you can place a gauge that tests vacuum? THERE IS A TEST PORT ON ALL DURAMAX 6.6L APPLICATIONS FROM LB7 TO LML. YOU CAN BUY THE GAUGE WITH FITTING FROM MANY VENDORS. 2. Also concerning the internal gear driven pump. Can those be replaced or the HPFP be rebuilt to save funds for those that have more time on there hands including the injectors. WE DONT REPLACE JUST THE INTERNAL DRIVE PUMP, WE REPLACE THE WHOLE INJECTION CP3 PUMP SINCE IT IS QUITE SOME TIME IN LABOR. BOSCH DOES HAVE IT AVAILABLE ON THEIR CATALOG. 3. If the ball inside the injectors is the weak point for older models does that mean they can be disassembled and replaced or the components be repaired to correct leakage? BOSCH AUTHROIZED REBUILDERS REPLACE THE WHOLE BALL AND SEAT ASSEMBLY IN THE REMAN OF THE INJECTOR. IT IS A PRECISE SETTING FOR THE TRAVEL OF THE PLUNGER, NOZZLE AND SHIMMING OF THIS ASSEMBLY. IT IS CHECKED AND CALIBRATED ON SPECIAL EQUIPMENT. 4. Do cp3 pumps needs to be timed or is that only for the cp4 pumps? GM MAKES NO MENTION OF CP3 PUMPS BUT DO FOR CP4. CP3 ON RAM 6.7L CUMMINS DO HAVE A TIMED SETTING. NOTE GM CP3 CAN HAVE AN OFF IDLE DIESEL KNOCK CAUSED BY HARMONICS THAT HAS NO EFFECT ON ENGINE DRIVEABILITY BUT IS CURED BY REMOVING THE CP3 PUMP AND MOVING THE GEAR 60 DEGREES THEN REINSTALL CP3 PUMP. 5. An how does the computer recognize if the pump is incorrectly installed does it throw a code? IT DOESNT KNOW. or is there a way you can monitor it with a scanner to see if it’s not timed properly? NO WAY TO KNOW. ALL A PUMP DOES IS SUCK AND PUMP there are so many questions I have but I’m extremely eager to learn... OK IM TIRED NOW.... HOPE THAT HELPS.
@@dieseltalkwithtonysalas8725 yes sir that helps!! Thank you so much for being informative. I will keep eyes for your videos to learn more like an apprentice. It’s a blessing when knowledge like this is shared. I truly appreciate learning everything I can
Hello Tony I have an 06 lbz and my problem is Truck cranks a lot to start, losses primeI rebuilt the filter head and changed the filter 2 times with 2 different brands and still no luck,replaced the hoses and just installed the whole filter head from extreme diesel and still doing the same thing. When I un screw the diesel cap to fuel up air gets sucked in like a vacuum I bought a new diesel cap for it and dose the same. The truck fills up with only 16 gallons so I'm guessing the tank has collapse thank you for you help
@Diesel Talk with Tony Salas no sir got 2 different ones online and one of them was oem. I found out not to long ago it needs motor mounts so return lines where getting a lot of air dur to the movement
Fuel Cap: Duramax LMM Vacuum / Vented I replaced the fuel cap with a locking cap. The cap is listed as vacuum-yes, vented-no Does this mean the new cap does NOT have a psi relief?
@@dieseltalkwithtonysalas8725 I was trying to relate your comment of the tank psi not releasing and causing air bubbles / low fuel rail issue. This would possibly cross over to the fuel cooler issue. I replaced the cap due to fuel costs and possible theft. It is a cap swap but can’t determine if this caused a problem. I have encountered 2 limp mode situations. Towing 9,500# trailer 80* OAT. Changing the fuel filter solved the problem but I am not confident as to when it will happen next. TP3018 filters only last 2,500-7,500 miles. Thank You for your fast replies:)
I have a 2004.5 / 2005 Chevy Silverado 6.6 LLY Duramax. Went to start ran for a few seconds cut off. Hasn't started since. Fuel tank was full but gauge went from full to empty. Went to mechanic and he said ficm was bad. Sent off for remanufactured put on today, still want start. Sent old ficm to be tested and the board was burnt and was not repairable. What could cause the gauge to go from full to empty and still not start. We primed to get air out of line and checked fuses all were good. I'm lost of what could be the problem.
So where you at with this vehicle? Get it started? FICMs on your LLY will trip codes. I have often repaired issue by simply cleaning connections on the FICM. But what codes are set and what is the desired and actual rail pressure while cranking? Need more info to help
Can you tell me why gm won't use lift pumps? And if we add one, any issues? What should max pressure be limited to on suction side (with pump) that won't cause issues?
Some say it’s Bosch some say it was Powertrain at GM. The bottom line many of us upgrade with an aftermarket lift pump. The new L5P is a Denso Common Rail and uses a lift pump. 3 phase pump actually. But to be fair if you look at the suction pump on the back of the CP3 or CP4 it’s a very stout pump. As for suction, GM says 4 inches at idle is max suction. Higher would be fuel filter restricted. But GM states the suction under load should be no more than 10’inches. I disagree on that. I have seen rail pressure drop at 8 inches. Thanks for commenting!
Got a question. Looking at a 2004 duramax LLY. Guy I know wants to get rid of it because its going to cost 15k to fix. huh? yeah I know. Dealer says it had fuel contamination and they found rust in the tank. Now I font that odd. Any thoughts? Maybe check the tank get a new one, replace sending unit blow out the lines, clean injectors and see if she runs. I could get a great deal on this but I am curious if you or anyone can come up with something im not thinking about or possible catastrophic failure or potential failures... Or in all just stay away from that problem. Thanks
Depends is it an 04 LLY or LB7? Injectors, lines add up but good quality Bosch. But we are under the assumption the issue is fuel related. What’s the asking price and how many miles on it?
Does the 2007 LMM have a dedicated post fuel injector that squirts fuel into the exhaust or is this done through the main injectors? I ask because I have the LMM in which the DPF was cut out, so What tells the injector(s) to squirt more fuel into the exhaust? I am not sure if this causes better or worse fuel economy?
No, the LMM uses post injections. This means it injects on the exhaust stroke of a cylinder to push that fuel into the exhaust towards the DOC.. it uses fuel consumed and pressure differential across the DPF to determine soot load on DPF. If DPF was eliminated there will be no post injections. Was truck tuned? Must have it you are driving it. What kind of fuel economy you getting?
@@bobbyboucher5309 that pump does not create enough volume and pressure. Go to xtreme diesel or Duramax store websites. They have lift pumps with or without filters ready to bolt on lift pumps.
Question for you sir 2016 duramax crank no start I already changed out fuel filter and no start so install new filter housing and still no start …. Codes it has are P0191 and P0088
First of all are you pumping the primer pump on the filter while trying to start it? Second you wouldn’t happen to have a tuner or code reader to know the fuel rail pressure? I need to review P0191 I know it’s a regulator but I look it up in the morning
@@dieseltalkwithtonysalas8725 truck is all stock no modifications but I do have a monitor and it’s showing 1.5 kpsi while cranking, I have tried priming it before start, priming while cranking, read a forum to spray small amount of starting fluid, so I did and truck started right up and stayed running but once I shut off and tried starting again I had the same issue all over again
If there is a high rail pressure issue, it comes down to the fuel pressure regulator which GM calls the FRPR. This applies to LB7 to LMM. For LML there is a high pressure regulator along with the FRPR. Note that if the truck has an aftermarket lift pump it can also cause a high pressure issue if regulator on it is not calibrated correctly.
Correct but I thought I mentioned they (vans) use an electric pump . It’s the only Bosch common rail on 6.6L that use an electric lift pump. Thanks for pointing that out!
Doesn't forward have a lawsuit on ACP 4? The CP4 has failures and many people have suffered on that. There is a lawsuit. Let's find out to see if they're paying for the breakdown and the contamination that shouldn't occur.
I got a weird situation where my brother just bought a 03 silverado. I noticed the scanner doesn't even turn on and I tried 2 of them. It cranks but no start. So I tried to bleed the system but the plastic screw broke. So I'm going to rebuild that pump tomorrow, hope it starts. Should I try anything else?
Check fuse, the connector where you plug in called the OBD Connector has to have power at pin 16. Usually this is tied in with the cigar lighter fuse. This might be why scan tool doesn't not turn on. You should have someone crank the engine while you pump the primer pump, bleed air fron the screw after you stop pumping on the plunger. Let me know!
@@dieseltalkwithtonysalas8725 I got it started!! Put in the new bleeder screw and bled it. Also the cig fuse was blown and it fixed the obd. Thanks a million!!
No plus cavitation is when there is a pressure drop due to a office or narrow opening This causing a pressure drop to the point you reach a boiling point. There are numerous videos on this subject you can search. However air works its way out through this common rail system. Think of it as burping it out the injector. Now I know about split tips like on HEUI system Caused by aeration but never seen it happen on these systems. But to answer your question, no but if it’s a suction system on these 2016 and earlier Duramax systems, you lose prime. Note on the LML with piezo common rail they air can destroy the CP4 Pump.
No it’s on the junction block But the aftermarket sells a plug which I recommend since the ECM can still shut it down in the event of over pressurization
Very informative video I do have a question. I keep getting a low rail pressure code when towing 8k car hauler with my 2006 lly duramax I have a hp tuners so I have been able to check balance rates and that seems good but every time it happens my fuel temp is around 170ish and it will command 26000 and drop to around 18000 to 22000. I have a lift pump besides that the truck is stock. I was wondering what your opinion on ppe fuel rail pug was And if the cascade valve on the cp3 could be bad. Befor I start pulling injectors and cp3 to be tested. Thanks
Most likely it’s the pressure relief valve It’s easy to diagnose. Simply get to the small return hose coming off the rear of drivers side rail and plug it . Then run a 6ft small hose attached to to that nipple on that rear rail where you pulled it and run the other end of the hose to your drivers seat with it inserted in a water bottle obviously empty. Go on a test drive, load it run it hard, if it squirts any fuel into bottle, definitely replace with ppe plug. If not then you need to get a vacuum pressure gauge made for Duramax and I can explain how you test cascade valve. Let me know.
To the CP3 in toward the transfer pump on the back of the CP3 pump itself. Then to the crankcase of the CP3 to lubricate it and to the MPROP or regulator that modulates the fuel volume to the high pressure plungers. Hope that helps! Thanks for watching!
@@dieseltalkwithtonysalas8725 I replaced the regulator at the same time I did injectors, could a torn or leaking o-ring on the FRPR cause a loss of prime at the filter head, the regulator is in a bad place to be able to see if it's leaking or not but I can't hear any fuel leaking or anything but primer wont get hard like it did before injector swap but will still fire up after about 10 seconds of cranking
@@maverickjohnson7534 I have never seen that but that’s why GM tells you to prime to 10 psi to check for leak internal and external. Need a gauge to check that. What year model you have?
I have a 2007 GMC Sierra 2500HD 6.6L and I'm getting a "Low Oil Pressure Stop Engine" message. When I start my car a message pops up saying oil change soon, but do note that I changed my oil and the oil pressure sensor 1,000 miles ago. When my car runs cold, the oil gauge reads normal (when i step on the gas it goes up as its supposed to). When my car reaches running temperature (~180F) the "Low Oil Pressure Stop Engine" message begins to appear. This happens when I come to a stop and gently step on the gas peddle. It happens for a second, then goes away. When my car is at running temperature and I step on the gas the pressure gauge needle barely moves. I've tried a code reader and nothing comes up. Is it safe to assume that a fuel injector might be leaking, diluting my motor oil?
If you have oil dilution you should see a rise in oil level on the dipstick. Second, are you using synthetic oil? But to check I would first check engine oil level and check for dilution. You can also put a droplet of the dipstick on a white paper towel and see if a ring forms around the droplet. If it does the oil is diluted. Then I would attach an oil pressure gauge to confirm oil pressure. Let me know
@@dieseltalkwithtonysalas8725 I believe there is a rise in oil level on the dipstick. I took some oil from the oil pan and it appears to be diluted and I feel like it smells like diesel. I'm not 100% sure though, I feel my mind is playing tricks on me. I saw a handful of people in a Duramax forum say that the paper towel test is unreliable. Thank you for the fast response.
@@dieseltalkwithtonysalas8725 Understand. I think the paper test is suitable for someone with experience (that I don't have). I think I'm just going to take it back to the GMC dealership. I really wanted to avoid this route, since they want to charge me $480 just to diagnose the truck. By any chance do you know any mechanics in southern California? Thanks for your help!
Thanks for asking! Will make another video on those engines. I do have training videos on my professional pay website but not on UA-cam. However the LML and LGH are BOSCH Piezo common rail which is completely different than early models.
High fuel rail pressure usually is the fuel pressure regulator on the injection pump unless it has an aftermarket lift pump where lift pump pressure is set to high Thanks for watching!
Hello , I have a question. Why do we need fuel cooler at the return-line to fuel tank? Do engine diesel engine must install fuel cooler in mandatory?? We have a problem with in-line 6 Diesel engine high pressure pump tappet roller damage. (damage at the high pressure pump tappet cylinder roller wear and it makes a fragments , which block the injector and Engine stops. When I checked the fuel tank, there were small metal particles , which from high pressure pump roller damage. I have to replace all fuel system because of this damage. I guess , if the fuel temperature is high at fuel tank, the diesel fuel viscosity drop and get damages at high pressure pump roller lubrication. Do we need fuel cooler at all diesel engines mandatory? Thanks and regard.
The pump problem you are having sounds like lubricity issue with the fuel. I have seen the issue you mentioned. But! Always remember water in fuel! If you think about it the pump is one of the hottest places in the common rail system. Therefore lube fuel in the pump with a substantial amount of water can have water separation in the pump crankcase destroy it due to lubricity. Now why the fuel cooler… it should be called a fuel condenser. It ensures no fuel in a vapor state goes back into the fuel tank. Imagine the right condition in the fuel system where it can be so hot with pressurized fuel and it changes from a liquid to a gas. By cooling the return fuel it ensures it stays in a liquid state. Hope that helps! Thanks for commenting!
Hey Tony I have an 08 van, which battery does the engine start from? Currently chasing stray voltage that keeps killing it after a few days with new batteries.
Both. Batteries are in parallel if I’m not mistaken. If you are draining battery I would do the test Light fuse pull trick. You first take one battery out of play by removing the positive battery terminal and leave it off Now the other battery you remove that battery positive terminal and put one end of the testlight on the terminal and the pointed end on the actual battery terminal. If there is a draw it will light. At that point start pulling fuses out one at a time and see where the light goes out. You use a non led testlight. The fuse that dims or turns the light off is the circuit with the draw. Make sure key is off.
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I have a LB7 when i start it the fuel wants to come back out the fuel cap almost like pressure is pushing it out even after I turn it off and remove the cap fuel will come out unless I wait 10 or 15 minutes I can take it off with no fuel coming out not sure why??
@@dieseltalkwithtonysalas8725 my fuel gauge is not working and it sounds like there’s a fast ticking noise from the tank I add diesel it pours out but it does slowly go back down I’m not sure if the tank is full or not this just happened today and didn’t add more fuel after…haven’t drove it in a while but I’ll try to add more fuel tomorrow and see
I'm a 1st time owner of a 06 lbz and this is informative. I've Learned alot about fuel rails and suction pumps. You are a professor! Thank you
Thanks for the comment!
What a great explanation and thank you for putting it in a way thats easy to understand, youve gained a subscriber. I'm having a hard start problem with my lb7, 10k on new injectors, airdog, cp3 and other supporting mods including fuel filter delete. When truck sits over night it starts absolutely perfect, after I shut it off I can immediately start it with no problem, if it starts to sit between 1/2 to approximately 2 hours it turns over a lot and sometimes won't start without starting fluid (I know! 😂) and if it does start it it starts at a low rpm and then revs up to normal. At the 3ish+ hours it starts normal again. No noticeable fuel leaks but it does have the original factory fuel lines from the tank. Any suggestions? I was thinking an air leak but didn't want to throw money at it guessing
Spent days researching why fuel is being pumped back to tank and never creating pressure! Finally the best breakdown of a system without u tube nonsense Thankyou for making this video I'm finally clear where my problems may be.
@@dbarnes7048 thanks for the positive comment. I appreciate it!
You said I’m trying to let you guys go and I got sad. I’m over here soaking as much information as I can! Great video
I am glad you feel you are learning. Thanks!
Tony, thank you so much for an excellent presentation. I have been wanting to add a lift pump to my 2005 GMC Sierra because I've seen lots of videos on you tube explaining the advantages of this. However, I was still hesitant because I didn't know exactly how the entire Duramax fuel system functioned. Thanks to you I now feel confident that adding a lift pump will be beneficial to my Duramax. Love your channel and keep the great videos coming.
Glad you learned from the video. We use xtreme diesel for pumps. Good people.
Been moving will have new videos up soon
Thanks for watching!
Thanks Tony for such a clear, concise video explaining how the early Duramax fuel system functions. I have subscribed to your channel and plan to see all of them. Thanks again!
I appreciate your comment! Hope the information helps! Thanks!
@@dieseltalkwithtonysalas8725 Tony I need help with my lly crank no start all of a sudden happened one time before and it was my ficm so I replaced it again thinking it was the same thing and no start any suggestions
Tony, thanks much for the great explanation! Just replaced the filter assembly after my LMM left me stranded in a parking lot. Realized I lost the prime due to failing seals in the assembly. Your explanation helped fill in the back story. Love the comment about idling when sitting there filling up - not sure why folks think they still have a 70's era diesel.
Glad it helped, thanks for commenting!
I have an LMM and experienced the same problem as you after a long drive from LA to Phoenix pulling our RV. I was able to re-prime with the hand primer to get it started and its been fine since. Nonetheless, I just ordered the fuel filter housing and am going to replace upon arrival. It appears to be an easy job, but any pointers?
I am having problems with my 2003 duramax 6.6 L not starting. It is a prime problem, but with your video. I have the confidence to fix the problem. Great information about the fuel system. Thank You
Glad it helped
Maaan!! I wish there was a ❤ button!!
I’m new to your channel Tony and thank you for your wisdom on this topic! I own a 04 GMC with a LB7. It has very low mileage and is in excellent condition. I’ve had struggled with electrical gremlin and now having fuel issues too.
I’m extremely happy I finally found your channel! 🙏🏻❤️
Sorry didnt respond sooner. With LB7 using a good fuel additive goes a long way.
There are some great upgrades like the banks big head and raise the boost from 20 to 27 psi. No prgramming needed and improves fuel economy
WOW, you are my new diesel god. GREAT instruction.
Glad you liked it!
Great education. Thx
My 03 D/max has had a lift pump since new.
Hopefully it helped! Thanks for watching!
Stuck duramax with crank no start, 185k on a 04. I am not a mechanic nor want to be but I guess forced in this case. Your video helped me understand the fuel system. Thank you. Fuel cap first, then the filter head, both oem from the factory.
04 was a year GM went from LB7 to LLY, which one you have? Have you also tried priming the pump on the filter while someone cranks it?
@@dieseltalkwithtonysalas8725 I have the 2004.5 truck with the lly. Tried the pump and crank process yesterday. The only thing that hasn't been replaced on this truck's fuel system is the injectors.
And thank you for responding to my post. Your video was very good. I learned a lot. thank you.
With regards to the fuel cooler.... hot diesel is of course "bigger" in volume. This reduces power! We were testing the output power of an 850KW generator, but couldn't get full power from it. I leaned on the fuel tank and noticed it was screaming hot. Seems the guys had just dumped a couple of jerry cans in there since it was just a quick test. As the return fuel dumped in, it just kept getting the fuel hotter and hotter! Output was down about 15% at the end. Not a small amount at that level.
I appreciate your u tube post. It was very educational for me. My truck died after a minute of running. I went to an online auto parts store and paid for a full housing like you mentioned it may be the way to go. Got the housing and installed. Sadly enough the primer pump leaked. Returned for a refund then decided just to go to the rebuilt kit. Another week later it arrived and I installed and yet again that primer plunger leaked. Both came from the same manufacturer. As funny as it sounds I put back my original seals on the primer housing and it kept the system vacuumed. Whether the other 3 o rings were at fault remains a mystery. For the price canadian 242 vs 27 I'd go with the rebuild kit. But the manufacturer that I dealt with and is very common failed to provide quality replacement and 3 weeks of truck sitting and trying to work in sub zero temp
No fuel getting to injectors
Why don't it start
Any ideas
HELP me PLSZ
@@BettyFowler-e3j there needs to be a vacuum in the fuel line on the duramax in order for fuel to get to the injectors. That vacuum comes from priming the fuel filter. The primer knob at the top should offer a bit of resistance when you push it down. If it's easy you don't have a vacuum. The o rings would need to be replaced in it and you can buy a ring kit and replace them very easily.
That I was searching for lift pump on 6.6 and didn't find nothing but thanks for the information now I know
I learn so much from your videos. Thank You for sharing your knowledge.
Thanks! Appreciate it! Another one coming later today!
Hello Tony, thanks so much for the great presentation! Nice diagrams and clear delivery! I am in the midst of replacing injectors on a 2004 LB7 with only 94k miles and there are two things I would really appreciate expert advice on:
1) On each side, the rear injectors had a load of gritty crud at the inlets, and corrosion outside the metal/metal sealing interface. Fairly clean at the front injectors and no corrosion, but both symptoms progressively worse towards the rear. Do you know what this would be from and how to protect against it?
2) I would like to leak test the installed return lines. I have seen a nice video of replacing the block banjo with a special one that allows the line and 4 injector return connections to be tested, and this does test all the line welds, but I don't have one and I would like to test the block connection too. The return line from the engine has the CP3 and the regulator on it ..... Would a vacuum or a pressure test be feasible on the line without leaking through or damaging those?
Thanks so much for your consideration of these things.
It is common to find grit on the inlet of the fuel injectors. How to reduce that? Fuel filters! I push for a supplement fuel filter to add.
Second, it is easier to buy a hand held vacuum pump from a local parts store. Vacuum test the return , may have to get creative with the plumbing but I have never had to on the LB7 s. Make sure you replace the banjo gaskets and torque to spec
Excellent video tony! Thank you!
Hello Tony, this is very informative, thank-you. I want to get a new fuel cap which has the pressure relief features built into the cap that you described to be so important. Would you please recommend a source for me to purchase that cap for my 2004.5 Chevrolet K2500HD Duramax 6.6L (LLY) truck? I have check the GM replacement parts, and don't see any that include the specs for the cap describing the pressure relief that you referred to.. Thank-you in advance, Bryan
We have a suspected air in fuel problem. The fllter head has been replaced with new OEM and still will kill once in a while then run smooth again. I recommended to my son to put a clear hose on the fuel return hopefully under the hood and run the clear line up under his windshield wiper to monitor while driving. Is this the easiest way to diagnose air in fuel? I'm thinking it HAS to be the issue but nothing is for sure so it'd be nice to confirm.
I still don’t trust filter head
I apply a vacuum using a hand held vacuum pump. This is done with a liquid separator
So the vacuum pump doesn’t suck fuel.
This is done at the outlet line of the fuel filter housing. You apply about 12 inches of vacuum and see if it holds.
If it doesn’t the filter head is leaking.
If that’s ok, how do you know it’s fuel related?
Do u have a scan tool or handheld to monitor fuel rail pressure?
Gracias. X su clase maestro gracias 22:02
Tengo otro website www.tornillosuelto.com
i learned plenty today thank you sir
this is an awesome training video definitely have shared with my technicians. Is there any way to bother you for the slides to utilize with the newer techs as we develop their skills to better their career?
Good day, some slides I can. Email me
Thanks for teaching us! Great presentation. Subscribed.
Great overview w tips. Not a mechanic but own an LB7
Thanks! Appreciate it!
Thank you, you explained everything well.
You're welcome!
Excellent video Tony!!! Thanks you
Thanks! Appreciate the comment!
Thanks for sharing your thoughts and knowledge with us! You videos are top notch! New subscriber!
Thanks and welcome
I’m in class .. learning. Have a 2093 1 ton Silverado..lost power and white smoke came out. Oil looks okay. No leaking . I also found out my fuel filter wasn’t put on right. So is leaking fuel -and won’t start. Though I see this video to know more about my fuel system
Thanks for commenting, you get it fixed?
Grrreat... after i bought TWO new green locking caps, aftermarket : /. Better go check them now, Really appreciate the heads-up! (is there any way to tell just by looking at the cap?) [Btw, used to work at a truck stop... can't Stand little boys who leave their diesels running at every store and fill up. Even in the cold, once it's up to temp, it just shows you're not smart)~ thx
at start up a diesel consumes more fuel than letting idle for 5 minutes
Very informative, awesome video! Any idea what would cause a high fuel rail pressure p0089 with a crank no start on a LLY?
Thanks for the comment! If high the first question is the truck modified with aftermarket lift pump? If not it could be an issue with the MPROP or fuel pressure regulator on the injection pump. But need to verify power to the connector and ensure there is no codes set for it.
@@dieseltalkwithtonysalas8725 Thanks for the response! The truck does not have a lift pump in it yet, is the MPROP the sensor on the passenger side fuel rail? The only code is the P0089
Tony...Excellent presentation and keen knowledge on your part. I have question.
Below you advise changing fuel filter every other oil change or 20k miles. My 16 LML goes 25k-40k miles before I have to change it. It also trips a change fuel filter light at about 14 in Hg I believe.
Now on my LBZ, I installed a vac gauge at bleeder port on fuel filter head and monitor that before I change it. When it gets close to 8 in Hg, I change it.
Also, I work in the filtration biz, and typically with single media filtration, the greater the differential pressure(vacuum in the case of a duramax fuel delivery arrangement), the more efficient your filtration will be until a)media breakthrough or b) a fully loaded media.
My question is at how many inches of Hg should a stock filter be changed?
First of all I say change filter every other oil change which is every 4k oil change which makes it every 8-9k.
If you are seeing 14 inches.. we’ll that s high
Spec from GM states no more than 10 inches
My spec is 8.
However! You have a LML. Those readings will hurt a CP4 pump.
But then again I recommend a lifer pump on those models.
Thanks for the comment!
I installed a lift pump on my 2010 LMM. Great option.
I hope it works great . Thanks for watching
@@dieseltalkwithtonysalas8725 It's been there about a month now, Very happy with it. I also bypassed and removed the engine bay fuel filter since the Air Dog has water separation and a filter.
Excellent Tony, Thank for the info, Question my 04 mid year Duramax LLY has a fuel controller you stated that the lly dint have one. did chevy used it on some then discontinue use? Thanks
You mean the FICM.
The 04-05 have one but the 06-07 LLY DOES NOT.
Hope it helps! Thanks for the comment!
More videos coming soon been slammed.
Got to Denver tomorrow to teach at a shop!
Thanks Tony very good information!!
Thank you! Appreciate the comment!
Dude I just subscribed to your channel thank you so much👍🏋️♀️🤗🤺
Hope it helps! Thanks for watching!
Tony I just want you to know that the fuel system you're talking about here does not suck the fuel from the tank. What is happening is the pressure in the supply line is being reduced allowing atmospheric pressure to push fuel through the system.
@@MylesSpengler don’t split hairs
Negative pressure on one side creates a low pressure under atmospheric absolute pressure. In our trade anything under atmospheric is considered a vacuum. This why we measure the suction in inches of mercury.
Suction is created to pull fuel from the tank to the injection pump
Atmospheric on one side in the tank which needs to be vented and low pressure suction on the other.
Geeez
New subscriber!! Loved the video! Just bought a '05 LLY with 376,000 miles with some issues,but nothing I can not fix myself with some research. I ha e a edge cts3 monitor and my e.c.t is showing -40 and the engine idles at 850 rpm so the ecm is making the engine rich to compensate. I have Ohms out the ect sensor and is reading zero,meaning the sensor is bad,I believe replacing the sensor will correct my problem? Your thoughts sir?!?!?!?
-40 degrees usually means an open in the circuit or short. ECT sensor should not have 0 ohms. It should have resistance. I would have to look it up what it should be since it varies with temperature. Check reference voltage to sensor, with key on, measure voltage across the tow terminals of the sensor, this is with the sensor disconnected, obviously should read 5 volts. Since the ECM thinks it is cold, it will idle up.
@@dieseltalkwithtonysalas8725 thank you
Fantastic video! Thank you very much!
Thanks for the comment! Appreciate it!
Hey Tony, thanks so much for the video man. you’re a godsend. you should have a diesel course for sale. i’m having a problem where my new fass pump is losing prime and my truck will die whilst driving. the rail pressure goes crazy and rpm is bouncing at idle. if i prime all the air it drives fine for a week maybe two and then it starts to act up again. having a sump installed on the bottom of the tank as well as a hp gauge for the rail. do you have any recommendations or anything? i’ve been stumped for a year on the issue and have gotten the cp3 and injectors rebuilt. entire system is new.
With the complaint you have I take a look at the pick up in the tank.
If the fuel levels runs low ti can lose prime on a high speed turn.
I would first run a line to a 5 gallon tank and see if the vehicle loses prime.
If not then need to check filter housing
Thanks for the information video but I have a couple qestions for you if you have some time. I have an lb7 Duramax completely stock replaced the injectors 10k miles ago has 315k now boshe reman injectors new hard-lines new seals o rings thermostat the whole 9 now I have fuel in my oil took the truck apart tore of the driver side cover and started it to look for fuel leak from the return line or possibly cracked injector. Nothing obvious so today I took appart the other side and did the same this time taking off the filter and adding uv due to it now I can’t seem to get the filter to prime I didn’t disconnect the Fcim banjos tried bleeding it from the housing and the hall valve nothing hear air and some times fuel but it won’t get hard. When I started the other driver side sat and ran fine no issues but the primer didn’t get hard either just bled some air out but that was without taking off filter or any rubber lines. Also had surging at low idle coming to a stop never a huge lose in power just the falling on its face for a second then kicking in when I was taking off like you had said in the end with air bubbles. I don’t know how to get this thing started again coild it lose prime through cp3? What tool would i need to test filter housing or could I make it? Thanks for your time I really appreciate it.
Ok a quick answer on one thing before I knock out .. long day
One to test filter housing you apply vacuum on the outlet line of the housing for a leak. Should hold vacuum.
Second, to find leak on high pressure side valve covers have to be removed. Disconnect regulator at the CP3 pump and IGN relay at the fuse box on the drivers side engine compartment. Have someone crank engine over while you use a colored led light to find a leak. The reason why we disconnect the regulator on CP3 is to go to max pressure and find leak. Reason why IGN relay is removed is it cuts power to FICM to engine won’t start.
Let me know… Tony
Just found your channel and learned a few things from this video. I replaced my cap on my LB7 with a locking one, how can I tell if it has the vent and relief valves.
Probably just a pressure relief valve but search that cap and look for specifications
Thanks for the comment!
Excellent video presentation. Thank you
Appreciate it! Thanks!
Tony, I have a question... reliability aside, might it be better to fit a CP4 onto an older engine? Higher psi is obviously better if the injectors can handle it, no? (btw... great explanation on the greater pumping volume of the CP4, ...But just for the record, the plungers are moving twice as much as the CP3, so might they wear out faster....?) thnk you
Sorry... Specifically: a CP4 onto a 2007 LBZ...?
The CP3 has done a great job. It’s isn’t surprising to see that pump go over 500K miles.
CP4 is a good pump but the low lift pump pressure and air can destroy it.
As time as come by many are realizing the pump isn’t that bad as thought.
Thanks for the comment!
@@georgehofgren6123 leave that CP3 in there! It’s a good pump! Keep fuel filter changed every other oil change. Use a good fuel additive once in a while.
Great video! Thank you.
You are welcome! Glad you liked it! Hope it helped!
Just found this video. Got a low fuel rail pressure code today and it went into limp mode an hr from home. Limped it to a friends house and immediately went to the filter head to check prime and no prime. Found no leaks. Replaced the fuel rail pressure relief valve and the filter head. Still had the problem. So I took the return line off the cooler and nothing came out. But as soon as I primed the the system it started flowing out pretty good. After watching this I'm leaning toward injectors. Your thoughts would be greatly appreciated as I'm about to start throwing more money at this pig. I don't want to do injectors right now bc of money and time it will be down for longer than I can afford. I was wondering if an aftermarket lift pump would solve this. Truck has 200k miles on it and bone stock everything.
Did you ever find out what it took to get your truck running again?
@@Trike. cp3
I loved this video, but I have a question. So this fuel pump has a mark to put it in timing, but I'm a little confused because the olds version of course needed timing because it worked mechanicly ,but in this case the system is controlled by sensor-modules-injectors means electronically and the pump function is generate pressure only. Why does it have a timing mark?
Happy Thanksgiving!
This pump simply sucks and pumps! There is no timing to be set. However! We have seen harmonics from the pump cause what we call an off idle diesel knock sound. Doesn’t affect performance of the engine but it’s annoying.
To fix this we remove the pump and move the gear 30 degrees. We reinstall. I can explain further this but it’s a big explanation!
So to be clear there is no timing mark or procedure to time the pump on LB7 to LMM.
Later model LML, LGH Duramax do have a timing mark.
RAM Cummins 6.7L due have a timing number etched on the CP3 shaft to set at 9 o clock .
Thanks for commenting!
Ty😊
@@davelosonczy1537 hopefully it helped you! Thanks for watching
Exellent!! Toni
Thank you! Thanks for watching !
I bought a 2004 duramax truck about a year ago with 129,000 miles. I only use it for firewood, gravel, and suchlike heavy duty chores. Otherwise, I dive my 4runner or Rav4 Hybrid that I don't need to worry about getting stranded in.
Long story short, I did essential upgrades to the truck (intake throat, lift pump, and trans cooler) and drove it only about 1,000 miles since I bought it. During that year, it stalled on with no warnings twice. First time, it started after 10-15 mins, the second time I had to disconnect batteries for a few minutes, and then it started. There are no fuel leaks. Yes, I despise gm (and suchlike) dearly but what the hell?!?
Any ideas?
Thank you in advance.
Ok is it a crank or no crank no start issue?
Need info.
You have access to a scan device?
@@dieseltalkwithtonysalas8725 It cranks fine, yes, I do have a professional Autel scanner. There was a code P0089 - Fuel pressure regulator performance caused by too high pressure from the lift pump. The first time it stalled before I installed the pump so I don't think it's related, and there were no codes.
Grat video thanks for the info
Thanks for the Comment!
is the CP3 pump the same pump no changes for all of these years ? is it just the fuel pressure regulator that has changed with the different model years?
LLY coughs on acceleration.. Change the fuel filter still same problem.. Fuel gauge stop working Could this be the problem? Should I add l lift pump while at it?
Awesome Detail on your video.
Thanks!!
Generally when a diesel coughs as you state it is not pressure related. It is usually a cylinder misfire or sensor issue from my experience. This is where I need to check all cylinders are operating and check fuel balancing rates.
By the fuel cap are you talking about the one on top of the tank or the one that you take off to fuel the truck
Fuel cap is always the one where you fill.
Thanks for commenting!
Thank you Tony for this video. Can you tell me, when i pump fuel from hand primer to cp3, have the cp3 to hold this pressure? Because i noticed, with engine off, fuel coming out in the return line to tank when i push the primer, the pressure is away after 1 minute, i can pump again.
My engine shut of after 10 Seconds, so i think high pressure side is good, no codes. 2003 lb7
@@pascalkobler1020 Good morning, when you pump on the primer pump towards the CP3, you also push fuel into the crankcase of the CP3 which also lubricates the internals of the pump. This lube fuel is regulated by the cascade valve on the CP3. So it is normal to see some fuel coming out of the return of the pump.
In diagnosis GM has a test you perform with the fuel pressure gauge. You pump the primer pump to 10 Psi and watch the rate of drop on the gauge. If it drops to 0 psi within a minute, replace the CP3 because the cascade valve is stuck open. Obviously this is done with engine off.
Hope that helps , getting up, make coffee
@@dieseltalkwithtonysalas8725 thank you for this clear information! If you come to Switzerland, i will invite you for coffee.
Test gauge is ordered, so i can check that.
Thank you!
Would you mind including a copy of the diagrams you posted in the description?
Great video! I installed reman bosch injectors on my lb7 and after about 200 miles of it driving fine it started blowing a large amount of white smoke under a load and feels like it's missing. I have a decent video of it but I'm not sure how to attach it. I had a code for maf sensor so I replaced that with the issue still being present. No loss of coolant or coolant smell from the exhaust. The only odd reading I'm seeing is mm³ of flow is almost double what's expected when this happens. Balance rates are all 0.0-0.1. Any ideas of where I should be looking?
Doubt it’s the MAF sensor.
White smoke is un burnt fuel.
Sounds like injector issue.
When looking at balancing rates? Can u see which injector is going above 4 mm3?
@@dieseltalkwithtonysalas8725 I believe the mm³ flow rate is measured across the entire fuel rail. Balance rates are in spec on all injectors.
I am studying diesel to provide new means for myself an because I’ve always done gas my whole life I purchased the book from my community college an read it every day , I am not a student but that by no means is limiting me to studying an learning this. I wanted to ask you. Concerning this system how do you actually test into the system to check for suction. Do they sell kits or is there a port that you can place a gauge that tests vacuum? Also concerning the internal gear driven pump. Can those be replaced or the HPFP be rebuilt to save funds for those that have more time on there hands including the injectors. If the ball inside the injectors is the weak point for older models does that mean they can be disassembled and replaced or the components be repaired to correct leakage? Do cp3 pumps needs to be timed or is that only for the cp4 pumps? An how does the computer recognize if the pump is incorrectly installed does it throw a code? or is there a way you can monitor it with a scanner to see if it’s not timed properly? there are so many questions I have but I’m extremely eager to learn.
Since I cant highlight replies, I can make them in CAPS.
1 Concerning this system how do you actually test into the system to check for suction. Do they sell kits or is there a port that you can place a gauge that tests vacuum?
THERE IS A TEST PORT ON ALL DURAMAX 6.6L APPLICATIONS FROM LB7 TO LML. YOU CAN BUY THE GAUGE WITH FITTING FROM MANY VENDORS.
2. Also concerning the internal gear driven pump. Can those be replaced or the HPFP be rebuilt to save funds for those that have more time on there hands including the injectors.
WE DONT REPLACE JUST THE INTERNAL DRIVE PUMP, WE REPLACE THE WHOLE INJECTION CP3 PUMP SINCE IT IS QUITE SOME TIME IN LABOR. BOSCH DOES HAVE IT AVAILABLE ON THEIR CATALOG.
3. If the ball inside the injectors is the weak point for older models does that mean they can be disassembled and replaced or the components be repaired to correct leakage?
BOSCH AUTHROIZED REBUILDERS REPLACE THE WHOLE BALL AND SEAT ASSEMBLY IN THE REMAN OF THE INJECTOR. IT IS A PRECISE SETTING FOR THE TRAVEL OF THE PLUNGER, NOZZLE AND SHIMMING OF THIS ASSEMBLY. IT IS CHECKED AND CALIBRATED ON SPECIAL EQUIPMENT.
4. Do cp3 pumps needs to be timed or is that only for the cp4 pumps?
GM MAKES NO MENTION OF CP3 PUMPS BUT DO FOR CP4. CP3 ON RAM 6.7L CUMMINS DO HAVE A TIMED SETTING. NOTE GM CP3 CAN HAVE AN OFF IDLE DIESEL KNOCK CAUSED BY HARMONICS THAT HAS NO EFFECT ON ENGINE DRIVEABILITY BUT IS CURED BY REMOVING THE CP3 PUMP AND MOVING THE GEAR 60 DEGREES THEN REINSTALL CP3 PUMP.
5. An how does the computer recognize if the pump is incorrectly installed does it throw a code? IT DOESNT KNOW.
or is there a way you can monitor it with a scanner to see if it’s not timed properly? NO WAY TO KNOW. ALL A PUMP DOES IS SUCK AND PUMP
there are so many questions I have but I’m extremely eager to learn...
OK IM TIRED NOW.... HOPE THAT HELPS.
@@dieseltalkwithtonysalas8725 yes sir that helps!! Thank you so much for being informative. I will keep eyes for your videos to learn more like an apprentice. It’s a blessing when knowledge like this is shared. I truly appreciate learning everything I can
Hello Tony I have an 06 lbz and my problem is
Truck cranks a lot to start, losses primeI rebuilt the filter head and changed the filter 2 times with 2 different brands and still no luck,replaced the hoses and just installed the whole filter head from extreme diesel and still doing the same thing. When I un screw the diesel cap to fuel up air gets sucked in like a vacuum I bought a new diesel cap for it and dose the same. The truck fills up with only 16 gallons so I'm guessing the tank has collapse thank you for you help
Busy week sorry!
Need to visually check the tank but did you buy cap from dealer?
@Diesel Talk with Tony Salas no sir got 2 different ones online and one of them was oem. I found out not to long ago it needs motor mounts so return lines where getting a lot of air dur to the movement
Fuel Cap: Duramax LMM
Vacuum / Vented
I replaced the fuel cap with a locking cap. The cap is listed as vacuum-yes, vented-no
Does this mean the new cap does NOT have a psi relief?
Locking cap is not the same, the cap for Duramax is unique, but you can vent it every often especially with diesel so high and perhaps a theft issue.
@@dieseltalkwithtonysalas8725
I was trying to relate your comment of the tank psi not releasing and causing air bubbles / low fuel rail issue. This would possibly cross over to the fuel cooler issue. I replaced the cap due to fuel costs and possible theft. It is a cap swap but can’t determine if this caused a problem. I have encountered 2 limp mode situations. Towing 9,500# trailer 80* OAT. Changing the fuel filter solved the problem but I am not confident as to when it will happen next. TP3018 filters only last 2,500-7,500 miles.
Thank You for your fast replies:)
wow. excellent video
Thank you very much!
I have a 2004.5 / 2005 Chevy Silverado 6.6 LLY Duramax. Went to start ran for a few seconds cut off. Hasn't started since. Fuel tank was full but gauge went from full to empty. Went to mechanic and he said ficm was bad. Sent off for remanufactured put on today, still want start. Sent old ficm to be tested and the board was burnt and was not repairable. What could cause the gauge to go from full to empty and still not start. We primed to get air out of line and checked fuses all were good. I'm lost of what could be the problem.
So where you at with this vehicle? Get it started?
FICMs on your LLY will trip codes. I have often repaired issue by simply cleaning connections on the FICM.
But what codes are set and what is the desired and actual rail pressure while cranking?
Need more info to help
Can you tell me why gm won't use lift pumps? And if we add one, any issues? What should max pressure be limited to on suction side (with pump) that won't cause issues?
Some say it’s Bosch some say it was Powertrain at GM. The bottom line many of us upgrade with an aftermarket lift pump. The new L5P is a Denso Common Rail and uses a lift pump. 3 phase pump actually.
But to be fair if you look at the suction pump on the back of the CP3 or CP4 it’s a very stout pump.
As for suction, GM says 4 inches at idle is max suction. Higher would be fuel filter restricted.
But GM states the suction under load should be no more than 10’inches. I disagree on that. I have seen rail pressure drop at 8 inches.
Thanks for commenting!
Got a question. Looking at a 2004 duramax LLY. Guy I know wants to get rid of it because its going to cost 15k to fix. huh? yeah I know. Dealer says it had fuel contamination and they found rust in the tank. Now I font that odd. Any thoughts? Maybe check the tank get a new one, replace sending unit blow out the lines, clean injectors and see if she runs. I could get a great deal on this but I am curious if you or anyone can come up with something im not thinking about or possible catastrophic failure or potential failures... Or in all just stay away from that problem. Thanks
Depends is it an 04 LLY or LB7?
Injectors, lines add up but good quality Bosch.
But we are under the assumption the issue is fuel related.
What’s the asking price and how many miles on it?
Awesome!!!!!
Thank you! Appreciate the comment!
I'm trying to figure out why my lly is spraying fuel on the hood on both sides after highway driving.
Does the 2007 LMM have a dedicated post fuel injector that squirts fuel into the exhaust or is this done through the main injectors? I ask because I have the LMM in which the DPF was cut out, so What tells the injector(s) to squirt more fuel into the exhaust? I am not sure if this causes better or worse fuel economy?
No, the LMM uses post injections. This means it injects on the exhaust stroke of a cylinder to push that fuel into the exhaust towards the DOC.. it uses fuel consumed and pressure differential across the DPF to determine soot load on DPF.
If DPF was eliminated there will be no post injections. Was truck tuned? Must have it you are driving it.
What kind of fuel economy you getting?
When testing to see if filter housing holds vacuum does the inlet hose need to be connected or does it not matter?
Does not need to be connected.
When I used to rebuild them I test them on a vise.
Thanks for watching
Cant i just use a carter lift pump from a 6.5 and stand alone filter heads to keep costs way down?
@@bobbyboucher5309 that pump does not create enough volume and pressure.
Go to xtreme diesel or Duramax store websites. They have lift pumps with or without filters ready to bolt on lift pumps.
Question for you sir 2016 duramax crank no start I already changed out fuel filter and no start so install new filter housing and still no start …. Codes it has are P0191 and P0088
First of all are you pumping the primer pump on the filter while trying to start it?
Second you wouldn’t happen to have a tuner or code reader to know the fuel rail pressure? I need to review P0191 I know it’s a regulator but I look it up in the morning
@@dieseltalkwithtonysalas8725 truck is all stock no modifications but I do have a monitor and it’s showing 1.5 kpsi while cranking, I have tried priming it before start, priming while cranking, read a forum to spray small amount of starting fluid, so I did and truck started right up and stayed running but once I shut off and tried starting again I had the same issue all over again
What about a High Rail pressure situation?
If there is a high rail pressure issue, it comes down to the fuel pressure regulator which GM calls the FRPR.
This applies to LB7 to LMM.
For LML there is a high pressure regulator along with the FRPR.
Note that if the truck has an aftermarket lift pump it can also cause a high pressure issue if regulator on it is not calibrated correctly.
What about the vans, they don't have any primer pump.
Correct but I thought I mentioned they (vans) use an electric pump . It’s the only Bosch common rail on 6.6L that use an electric lift pump. Thanks for pointing that out!
Do you know where the lift pumps are located in the vans, thanks Tony.
Doesn't forward have a lawsuit on ACP 4? The CP4 has failures and many people have suffered on that. There is a lawsuit. Let's find out to see if they're paying for the breakdown and the contamination that shouldn't occur.
I got a weird situation where my brother just bought a 03 silverado. I noticed the scanner doesn't even turn on and I tried 2 of them. It cranks but no start. So I tried to bleed the system but the plastic screw broke. So I'm going to rebuild that pump tomorrow, hope it starts. Should I try anything else?
Check fuse, the connector where you plug in called the OBD Connector has to have power at pin 16. Usually this is tied in with the cigar lighter fuse. This might be why scan tool doesn't not turn on. You should have someone crank the engine while you pump the primer pump, bleed air fron the screw after you stop pumping on the plunger.
Let me know!
@@dieseltalkwithtonysalas8725 would the obd2 port not working cause a no start?
Yes sir, but you mentioned the scan tool didnt power up. does it turn on ?@@pabloso8403
@@dieseltalkwithtonysalas8725 I got it started!! Put in the new bleeder screw and bled it. Also the cig fuse was blown and it fixed the obd. Thanks a million!!
Does aeration in the system cause destructive cavitation?
No plus cavitation is when there is a pressure drop due to a office or narrow opening
This causing a pressure drop to the point you reach a boiling point.
There are numerous videos on this subject you can search.
However air works its way out through this common rail system. Think of it as burping it out the injector.
Now I know about split tips like on HEUI system
Caused by aeration but never seen it happen on these systems.
But to answer your question, no but if it’s a suction system on these 2016 and earlier Duramax systems, you lose prime.
Note on the LML with piezo common rail they air can destroy the CP4 Pump.
Is there a fuel pressure relief on the LB7 rail
No it’s on the junction block
But the aftermarket sells a plug which I recommend since the ECM can still shut it down in the event of over pressurization
Very informative video
I do have a question. I keep getting a low rail pressure code when towing 8k car hauler with my 2006 lly duramax I have a hp tuners so I have been able to check balance rates and that seems good but every time it happens my fuel temp is around 170ish and it will command 26000 and drop to around 18000 to 22000. I have a lift pump besides that the truck is stock. I was wondering what your opinion on ppe fuel rail pug was And if the cascade valve on the cp3 could be bad. Befor I start pulling injectors and cp3 to be tested. Thanks
Most likely it’s the pressure relief valve
It’s easy to diagnose. Simply get to the small return hose coming off the rear of drivers side rail and plug it . Then run a 6ft small hose attached to to that nipple on that rear rail where you pulled it and run the other end of the hose to your drivers seat with it inserted in a water bottle obviously empty. Go on a test drive, load it run it hard, if it squirts any fuel into bottle, definitely replace with ppe plug. If not then you need to get a vacuum pressure gauge made for Duramax and I can explain how you test cascade valve.
Let me know.
Does the hand primer send fuel all the way to the injectors or does it pressurize between the filter head and the cp3?
To the CP3 in toward the transfer pump on the back of the CP3 pump itself. Then to the crankcase of the CP3 to lubricate it and to the MPROP or regulator that modulates the fuel volume to the high pressure plungers.
Hope that helps! Thanks for watching!
@@dieseltalkwithtonysalas8725 I replaced the regulator at the same time I did injectors, could a torn or leaking o-ring on the FRPR cause a loss of prime at the filter head, the regulator is in a bad place to be able to see if it's leaking or not but I can't hear any fuel leaking or anything but primer wont get hard like it did before injector swap but will still fire up after about 10 seconds of cranking
@@maverickjohnson7534 I have never seen that but that’s why GM tells you to prime to 10 psi to check for leak internal and external.
Need a gauge to check that.
What year model you have?
@@dieseltalkwithtonysalas8725 2002 lb7
I have a 2007 GMC Sierra 2500HD 6.6L and I'm getting a "Low Oil Pressure Stop Engine" message. When I start my car a message pops up saying oil change soon, but do note that I changed my oil and the oil pressure sensor 1,000 miles ago. When my car runs cold, the oil gauge reads normal (when i step on the gas it goes up as its supposed to). When my car reaches running temperature (~180F) the "Low Oil Pressure Stop Engine" message begins to appear. This happens when I come to a stop and gently step on the gas peddle. It happens for a second, then goes away. When my car is at running temperature and I step on the gas the pressure gauge needle barely moves. I've tried a code reader and nothing comes up. Is it safe to assume that a fuel injector might be leaking, diluting my motor oil?
If you have oil dilution you should see a rise in oil level on the dipstick.
Second, are you using synthetic oil?
But to check I would first check engine oil level and check for dilution. You can also put a droplet of the dipstick on a white paper towel and see if a ring forms around the droplet. If it does the oil is diluted.
Then I would attach an oil pressure gauge to confirm oil pressure.
Let me know
@@dieseltalkwithtonysalas8725 I believe there is a rise in oil level on the dipstick. I took some oil from the oil pan and it appears to be diluted and I feel like it smells like diesel. I'm not 100% sure though, I feel my mind is playing tricks on me. I saw a handful of people in a Duramax forum say that the paper towel test is unreliable. Thank you for the fast response.
@@miguelfajardo9703Really? Not my experience
It has worked great for me.
@@dieseltalkwithtonysalas8725 Understand. I think the paper test is suitable for someone with experience (that I don't have). I think I'm just going to take it back to the GMC dealership. I really wanted to avoid this route, since they want to charge me $480 just to diagnose the truck. By any chance do you know any mechanics in southern California? Thanks for your help!
@@miguelfajardo9703 as I train shops, why not look for a shop near you.
Look at their reviews. Plus Bosch has shop network as well.
WHY are the LML and LGH not mentioned?
Thanks for asking! Will make another video on those engines. I do have training videos on my professional pay website but not on UA-cam.
However the LML and LGH are BOSCH Piezo common rail which is completely different than early models.
Can you explain why I get a p0088 high pressure code
High fuel rail pressure usually is the fuel pressure regulator on the injection pump unless it has an aftermarket lift pump where lift pump pressure is set to high
Thanks for watching!
Hello , I have a question. Why do we need fuel cooler at the return-line to fuel tank? Do engine diesel engine must install fuel cooler in mandatory??
We have a problem with in-line 6 Diesel engine high pressure pump tappet roller damage. (damage at the high pressure pump tappet cylinder roller wear and it makes a fragments , which block the injector and Engine stops.
When I checked the fuel tank, there were small metal particles , which from high pressure pump roller damage.
I have to replace all fuel system because of this damage.
I guess , if the fuel temperature is high at fuel tank, the diesel fuel viscosity drop and get damages at high pressure pump roller lubrication.
Do we need fuel cooler at all diesel engines mandatory?
Thanks and regard.
The pump problem you are having sounds like lubricity issue with the fuel. I have seen the issue you mentioned. But! Always remember water in fuel! If you think about it the pump is one of the hottest places in the common rail system. Therefore lube fuel in the pump with a substantial amount of water can have water separation in the pump crankcase destroy it due to lubricity.
Now why the fuel cooler… it should be called a fuel condenser. It ensures no fuel in a vapor state goes back into the fuel tank. Imagine the right condition in the fuel system where it can be so hot with pressurized fuel and it changes from a liquid to a gas. By cooling the return fuel it ensures it stays in a liquid state.
Hope that helps! Thanks for commenting!
Hello Tony I have a 2005 duramax installed new fuel pump and I can't seem to get gas past the fuel filter . Can you please help .
Which pump? The cp3 injection pump?
Merry Christmas!
@dieseltalkwithtonysalas8725 yes sir
Hey Tony I have an 08 van, which battery does the engine start from? Currently chasing stray voltage that keeps killing it after a few days with new batteries.
Both. Batteries are in parallel if I’m not mistaken.
If you are draining battery I would do the test Light fuse pull trick. You first take one battery out of play by removing the positive battery terminal and leave it off
Now the other battery you remove that battery positive terminal and put one end of the testlight on the terminal and the pointed end on the actual battery terminal. If there is a draw it will light. At that point start pulling fuses out one at a time and see where the light goes out.
You use a non led testlight.
The fuse that dims or turns the light off is the circuit with the draw. Make sure key is off.
@@dieseltalkwithtonysalas8725 Thank you I'll try it!
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Can bad gas cap give code P1093?
No
I believe it is a fuel rail pressure code
Which year model you have?
It's a 2002 gmc sierra 2500hd 4x4 duramax LB7
Also have code P0102
I connector a guage to fuel test port gauge was reading 6 inHg vac
Federal emission.
I have a LB7 when i start it the fuel wants to come back out the fuel cap almost like pressure is pushing it out even after I turn it off and remove the cap fuel will come out unless I wait 10 or 15 minutes I can take it off with no fuel coming out not sure why??
Sounds like high pressure is on the return side.
But what is the level in the tank when this occurs?
@@dieseltalkwithtonysalas8725 my fuel gauge is not working and it sounds like there’s a fast ticking noise from the tank I add diesel it pours out but it does slowly go back down I’m not sure if the tank is full or not this just happened today and didn’t add more fuel after…haven’t drove it in a while but I’ll try to add more fuel tomorrow and see
Truck will not start
0:37
Not sure what you mean