Hard to believe that the fuel was so dirty in the bowl. I recently installed a new carb on a WX-10 Honda water pump and it ran great. Three days later the guy said it won't start. New carb was full of Rusty gas and water. I replaced it again and took it to his house and saw the old rusty gas can he was using. The fuel must have been 3 yrs. old and the inside of tha can was all rust. He swore he used new gas, and then blamed his kids for using old gas. I told him not to bring it to me again. Thanks for the video.
We replaced around 75 % on riding mower that are 5/10 years old They rot on inside of the cap and most mechanic think it’s fuel hose Rubber really rotten in tinny peace’s
That was almost super unsatisfying until you found the gas cap issue. Always nice to find something you can definitively point to as the issue. Nice work.
Once again James’s attention to detail found and issue I wouldn’t have even thought of, and once pointed out made perfect sense! Great video I now have another item to search for when working on small engines
James, our lawn mower would not stay running. Replaced fuel, air filter, spark plug, and blade. As soon as the prime burned, the engine quit. Watched your video. Went outside, loosened the cap…magic! It ran great! You are a genius my friend. Gravity feed systems need that head pressure in the tank or the engine will starve. Thank you. Next stop, new gas cap. Cheers!
My guess that I posted is that it vents from those rectangle holes at the bottom of the cap. The long and narrow paths eventually got clogged up. Ultrasonic will most likely clear it up.
I don't think it is ment to vent unless the pressure is high enough. (think pressure cooker or hot water tank) The cap is ment to keep the Ethanol under pressure to prevent it from evaporating. Just like the new gas cans.
@@MM-wt8oc How would it do that? Where is the pressure coming from? Are you saying when it runs the pressure will rise and then the cap will retain the pressure while it is in the garage over the winter? The problem with such a design (assuming it's possible) is that if the tank holds pressure above 1atmosphere (only possible if it seals), then as the fuel drains while you are running it, air cannot get into the tank and if the pressure in the tank is lower than the pressure in the bowl, it won't flow. It's like when you dunk a straw in a soda and then cover the end of the straw and lift it out and the straw doesn't drain.
@@tarstarkusz he is saying when the pressure drops as the tank tries to provide fuel to the carburator and the cap does not vent creating a low presure in the tank, he also explained that it can cause issues if the tank gets warmer from winter to summer causing the tank to swell under extra pressure ((2 seperate issues from the same problem lol) this video actually solved an issue I was having with a generator (I didn't even think the small air his when I opened the cap was an issue, I was wrong lol)
What you do is amazing. When I was a kid in school that was gonna be my career yeah, fix small engines, but my high school shop teacher told me don’t do it cuz there’s very little money in it.
I love the the thought process you use troubleshooting these kind of things. I probably would have just drilled a small hole in the old cap instead of buying one, but Im cheap like that.
Here is why I really liked this one. Many years ago (many, many), I had a British sports car. It had suffered minor body damage from a parallel parker, near the fuel filler. Picked it up from the body shop, and it died on me on the way home. I was mystified: the car had always run flawlessly, and the body repairs had nothing to do with anything under the hood. (Er, “bonnet.”) Before getting out tools (something one always carried with British cars) and fiddling with the carbs, I decided to smell the fuel in the tank. Spun off the cap and heard the air rushing in. Left the cap off, drove to an auto parts store, bought a vented cap, and drove home no issue. Apparently the body shop had replaced the filler cap and, back then, one had to be sensitive to whether a given vehicle required a vented or unvented cap. All that said, I got all the way through this video and never thought about the cap. Oh, well.
I remember the metal caps with a vent hole. I miss those days. I still use my 1965 Briggs. I've replaced the rings once in 1988 or so. Did the valves too, since the head was off. Outside of replacing the rope a few times, never a problem. It was my grandparents mower. I keep the oil changed and run it empty every fall. It'll get passed on. Bad cap....that took some thinking cap. Great work.
Some times James things like that just slip's pass , no body at fault here, it is just one of those thing's. great catch thou, good video. keep up the good work.
What a pain but a very good lesson to remember. Always check the simple things first which is sometimes hard to remember to do. Great diagnosis for sure. Thanks for the videos.
Similar to an issue I had w my 40+ yr old Stihl chainsaw. Had me perplexed for a while.It came up when I serviced the saw and replaced the fuel and vent lines. To vent Stihl placed about a 1/8” set screw in the end of the vent tube. Thinking must’ve been that air could work its way past the threads but sawdust wouldn’t. Saw would start easily, run great for a minute or two but would starve and die. Finally figured out the new fuel line I’d installed was much more supple than the old and the set screw moulded to the line so no venting. Found small air filter like ends on the internet that push into the end of the vent line and ‘voila’ runs great. Never miss any of your vid’s.
I've been watching your channel for a while as I tinker with generator and lawnmower repairs, I've had a renegade generator sitting for a long time that had me stumped and had a lot of parts and effort put into it, I saw this video and took the cap off when testing it to find I had the same issue, it took longer to show due to the larger tank but after several runs that was indeed the issue, credit to you, an unsellable generator has now past its testing and been sold, your videos have helped on many occassions and it's appreciated
@@jcondon1 question for you, I delivered an 8kv generator to a friends farm where he was getting solar and batteries as back up which would also power pumps if needed, the electrician set the power of the solar to cut off the grid power I'm the event of a blackout and wired an earth to the frame of the generator and earth of the generator 240v plug and had it set up to run alongside the solar in the event of a blackout or fire, he just explained simply that this was so if their was a short the solar wouldn't be harmed, I didn't question him further as he was a little shirt on manners and busy, I am wondering if you could explain this in one of your videos, their are other videos about Wether to earth a generator or not (which was no help to this question and not clearly explained in layman's terms), just an idea, love the videos, so many helpful tips in assessing and repairing and much appreciated
Inside the bad cap is probably a valve, similar to the disk valve in a vehicle's radiator cap. That lets it build pressure to a certain level before releasing, but also allows a vacuum to open the valve. Gummy-goo ethanol gas glued the valve or it's holes shut, thus you had excessive pressure and no vacuum admittance. Let's have a cap deconstruction to see what's going on with the bugger 😉
I love your channel. I appreciate the fact that you make sure your torque pretty much every bolt to speck. In my opinion, it's important but not alot of other small engines mechanics just don't do it. Thank you James for sharing your skills with us.
@justjeff4640 First tightening or turning a bolt eventually will create tension. The tension in the bolt provides the clamping force on the parts being held together. Not enough torque causes the clamping force to be insufficient, it vibrates loose when machine is used. Too much torque can strip threads and/or distort materials being joined.
Thanks for these excellent videos! I've run into this twice on string trimmers. The first time you encounter this problem, you doubt your sanity because the engine appears to have everything it needs to run.
Wow, in all these years, I’ve never seen an issue like that with a mower gas cap. I’ve seen it plenty of times with portable outboard motor tanks that have a vent screw in the cap, but not those push mower caps. Great video as always!
Thank you for this one James. You certainly come up against some rare faults. I have seen you check gas tank fuel caps before if you suspect a possible airlock in the fuel system. This is the first time that I have seen you find one though. I must be cheaper than you because I would just have drilled a very small hole in the cap to allow the passage of air. A size 80 gauge drill bit with a diameter of 13.5 thou would be fine. It would have saved five dollars. Thats just me. I am sure that your approach is more professional.
A while back, I was given the exact same lawnmower with the exact same problem, and like James, I went through the same procedures until I found the problem. looking into the tank, I saw a very small white plastic tube in the intake and not knowing that it was some sort of filter, I pulled it out. Didn't fix the problem, but it ran with the cap off. Put the cap back on and engine quit a couple of minutes later. I pulled the fuel line off at the tank and no flow. Opened the cap to look in and gas started flowing. Put the cap on and it stopped. Upon examining the cap, I found no air vent hole, so I peeled back the little rubber gasket inside and drilled a .030 dia. hole thru the top of the cap and it ran fine. The other owner had taken it to two different shops, and they couldn't fix it. New air filter and blade sharpening and sold it for $120.00. Next time, I'll start with the cap. I would be worried about the "dished" cap letting water in. Where is the vent hole? Mine was domed.
@@mtcman42 Well it worked. You are right in worrying about the shape of the cap possibly letting water in. Choosing where to drill the hole then needs care. At the conclusion of James' video, his solution was to buy another cap with the vent hole designed into it. The designers of that cap obviously had the same problem to consider and must have acted on their view of it. It would be good to see the exact design of James' new cap as you say.
I decided to revisit the video. At 24 minutes in we can see the new cap as James looks at it. From there to 25 minutes James points to the hole in the cap. The top of that cap is definitely concave. That would certainly hold water. The hole is not at the bottom but some way up toward the rim. Perhaps to reduce the risk of water ingress. The diameter of the hole would influence the possible inflow of water. The bigger the hole the bigger the risk. I wonder what the size of the hole is in James new cap.
@@r8118830Water needs a larger hole than air. Drain holes for water are usually 5 mm. Air vents can be smaller. That said why not have a dome on cap? Many systems vent fuel tanks with a hose to the carb area, another proven design.
That's certainly amongst the LESS COMMON issues that turn up. It's nice that the outdoor temperatures helped by giving you an audio cue. That's certainly not the first thing you'd think of when you have an issue such as this. Vapor lock was one of my thoughts at the beginning, when I heard it "runs for awhile"...... so I was wasn't way on the moon with that idea.
I own a mower with a gas cap that has a deep vertical groove cut into the threads. I doubt it will ever fail venting. Any cap with a pinhole will sooner or later plug.
I really appreciate your videos. It gives me confidence I can keep my equipment running, because you describe in your videos the steps you go through when troubleshooting issues. I am also going to (not) read the comments until AFTER watching the video. It can be like reading the last chapter in a book first.
Great video , showed good trouble shooting methods . Also shows how one thing or system affects the other .This is hard to demonstrate in this field .Thanks again for taking the time .
Great diagnosis and easy to overlook. I had this same issue with a couple of older Honda HR214 mowers. Honda used a foam filter material inside their gas cap vent passage to keep dirt out (they still do). Unfortunately the old foam broke down and solidified over time blocking the vent and causing the engine to starve after about 10 minutes or so. I replaced the foam and they both ran great after that. Briggs also went through a few gas cap design changes in an attempt to “improve” things and they ended up with the horrible design they have now. It’s a half-turn cap that won’t stay tight, leaks fuel all over and traps grass clippings and dirt under the edge that fall into the tank when you open it. Simpler is better IMO, that cap you bought was always their best design.
James as always you have the golden touch. My 1850 Colman Genorator was beginning to act up and after watching your post went and bought a new spark plug and it now runs better had an R in it and ran test and had very low omes. But the gas tank cap was a home run and great to see that you were able to get it fixed that's something that I wouldn't have even give it a thought. Good Job.
Great video! I had the same issue and it took me forever to find the answer. I drilled a couple holes in the cap, and it fixed the issue. However, engine vibration caused gas to spray everywhere. I had to replace the cap anyway. Thanks!
I sure learned something new today. I hope your friend isn't leaving that mower exposed to the elements. The cup shape of the top of the cap combined with a vent hole could spell trouble in the rain.
Nice catch! As you progressed through your problem solving approach, the cap was the last item on the list. Just goes to show that it's not a common problem, but not one to over look.
I had the same cap vent issue on a motorcycle. Tighten cap - stalled. Left cap loose ran like a champ. Replaced cap - no further worries. Great videos.
Thanks for a very interesting video. I will tuck that in my mind. About the time we figure out all the little tips, tricks, and traps to small engines everything will have gone electric! Good analysis on this.
Had same issue with my B&S quantum. Replaced the cap with same one you did and fixed it. Same issue on our 25 year old snowblower with Tecumseh motor. New cap fixed that too.
Had that happen on my JD lawn tractor. After mowing for a while it would die and backfire and it would not start. I would go in the house for a while and it would restart only to do it again after a little while. When I figured it out I just pounded a nail through the hole that was supposed to vent and no more problems. That was 6 years ago and I'm still using that old tractor.
Jim: I do whatch your videls all the time and do all by own mower repairs. Put a new carb. on a Kohler engine. Engin ran too fast. Found interferance on large carb gasket. Cut a small piece out noy guns great when it starts. I am having the exact same problem. I have to use starter fluid to get it bto start. It does run but needs starter fluid fore every start. I was going to clean the new carberator but you may have saved me much time. Thank you.
Another top quality video. Thank you Donny. I have come across all these issues with customer machines. the vent problem happens a lot on Tecumseh snowblower caps that fall apart. No matter what machine, what works for me that I advise all my customers to do is keep the fuel tanks completely full at ALL TIMES with premium. Any container left in temperature change will get condensation resulting in water in the carburetor. If the machine has a shut off fuel valve I turn off the fuel and run it till it quits before storage.
I have one of those mowers that does something very similar. I will have to try a new plug and a new fuel cap. The carb is good, so I guess that's my next step. Thanks for posting this.
Another truly fine bit of detective work James. I've had this problem in the past; it can be a real toughie to figure out. Thanks again for another fine video. God bless. Rev. D.
That's why I finally switched to a battery mower.... Still love my gas backpack blower for the ton of leaves we get in fall but every week mowing is now quiet and reliable....and way less stinky. As soon as good blowers are available in battery I'm switching. But you can take my 2 stage gas snowblower out of my cold dead hands. I live in MN....
The engiine looks like a newer version of the Briggs 4.5 Quantum. My mother bought a new TORO GTS2 back in June, 1995. It has a 4.5 Quantum on it too. My mom passed away in Sep 2020, but I still have that old mower, and it still runs. It got a small piece of plastic or crud stuck in the carb back in May-June of 2005. A carb rebuild kit & cleaning fixed it. It got dirt in it once after that, so I knew what to do. It doesn't have very good compression, after all these years now. But I still use it a few times a year to mow part of a shooting range target area about 12 miles from me. It still gets the job done. I also have TWO spare identical used engiines that also run. When the current engiine shits-the-bed, I will swap out the engiine.
I love your videos. I will never fast forward thru any part of your videos for fear of missing something. I can't say that about many other videos. I had a Troybuilt with the same problem. Drove me crazy until I finally figured it out. Because I had this problem, I suspected that that might be your problem.
The vent on my riding mower slowly got clogged over time unbeknownst to me and caused the same issue. The darn thing would run for 20 minutes that way and slowly lean out! Once I discovered the blocked vent on the fuel cap, loosening it solved the problem, but not before numerous carb cleanings, carb kits and tank cleanings! This had been going on for a couple years, and exhibit itself on hot days too!
Got one like that, but It has the good cap. At times I have some troubles with the kill handle....sometimes I have to pull harder on the cable. Thanks for the nice video, very helping.
Well done James, your friend will be delighted. But a 3 hour drive to deliver it, it might be cheaper to send it by courier - the price of fuel these days. Thanks for sharing
@16:00 you were testing fuel flow, I grabbed a cigarette to smoke, but quickly returned the lighter before igniting it fearing the vapor of the fuel to burn. Then I remembered it was only a video 😁
I was hoping you were going to take apart the old cap to figure out how and why it wasn't venting properly. May just have dirt in it and needed to be soaked or cleaned. Great video!
Thanks, James. I already knew about the failed fuel cap check valve syndrome, but hadn’t seen one of those DIY fuel drain hoses. Just made myself up one and put a length of duct tape around it so there’s no mistaking it’s a tool. I may hose clamp on some sort of wire eye with which to hang it up near my fuel containers. 👍🔧🧰
If I am not mistaken most caps are designed to hold pressure to keep the fumes in the tank for EPA/CARB compliance. They also have a one-way valve to prevent vacuum in the tank. Had a pressure washer that did the same thing as this mower. The cap on the tank was able to be disassembled and I found the valve to be similar to a MTD 2 stroke fuel cap. the ones with the little slotted rubber nipple for the valve.
I had a similar behaviour on my Toro, eventually I found out that the auto choke was broken. I changed the auto choke and since then the machine works flawlessly.
Gas caps are something that can be easily overlooked and that have a big influence on small engine performance. Maybe something to be added to your future list of things to check.
I’m having a similar loss of power in my Troy Built with a Honda engine push mower which is becoming more difficult to start. I’ve put in fresh gas, Octane 94, a new NGK spark plug OEM, replaced the air filter, changed the oil, but tipped it once on the wrong side. I’m still puzzled so far. Thank you for your excellent video and diagnosis!
The original cap is known to go bad. Probably some emissions garbage. Anyway I took one apart a long time back and I believe it has 2 spring loaded plastic valves in it. With the cap you added I will recommend a in-line fuel filter and tell your buddy do not leave it outside. Water will get into the tank. Nice find btw.
I think the reason there are 2 very different fuel caps listed for this engine is that the original cap is required to meet EPA clean air requirements mostly for the state of California the replacement cap is a noncompliant version.
I did not see that fuel cap thing coming,, my money was on the autochoke.. The replacement cap you got is the exact cap that my 2009 personal pace came with and is still on it...
Hard to believe that the fuel was so dirty in the bowl. I recently installed a new carb on a WX-10 Honda water pump and it ran great. Three days later the guy said it won't start. New carb was full of Rusty gas and water. I replaced it again and took it to his house and saw the old rusty gas can he was using. The fuel must have been 3 yrs. old and the inside of tha can was all rust. He swore he used new gas, and then blamed his kids for using old gas. I told him not to bring it to me again. Thanks for the video.
@@gags730
Small in-line fuel filter between the gas tank and the carb on every mower would sort this rust problem out....
Yes. Non mechanical people are the worst enemies to their own equipment.
I give you a ton of credit for your thoroughness and perseverance! Most people would never have found that problem.
Thoroughness*
🙂✌️❤
@@kajem575 I'm not much for spelling. New phone and spell check must have left me down!
@@chuckmayerchak3071 Ahh we all do it. Hey,you got perseverance right. My prob. is usually small keyboard as to size of fingers causing typos.
🙂✌️❤
True!
First thing I check when an items given or brought to me is the cap. Learned that the hard way years ago.
I thought it was a fuel problem but the gas cap was a new one to me also, great job!
We replaced around 75 % on riding mower that are 5/10 years old
They rot on inside of the cap and most mechanic think it’s fuel hose
Rubber really rotten in tinny peace’s
I think I might I have the same problem fuel cap.
That was almost super unsatisfying until you found the gas cap issue. Always nice to find something you can definitively point to as the issue. Nice work.
That woof at the end of the credits always gets me :D
Good video! Who would of ever thought a fuel cap?
Once again James’s attention to detail found and issue I wouldn’t have even thought of, and once pointed out made perfect sense! Great video I now have another item to search for when working on small engines
James, our lawn mower would not stay running. Replaced fuel, air filter, spark plug, and blade. As soon as the prime burned, the engine quit. Watched your video. Went outside, loosened the cap…magic! It ran great! You are a genius my friend. Gravity feed systems need that head pressure in the tank or the engine will starve. Thank you. Next stop, new gas cap. Cheers!
That can be a hard one to diagnose. Easy fix though.
Nice find. That's probably the last thing you would suspect but it just goes to show it's often the simplest thing causing the problem.
Another fantastic video from the small engine master thank you James your tenacity is incredible!
It would be interesting to determine how the original cap was supposed to vent and why it failed.
I think he should try to rebuild it. That way he can figure out how it is supposed to work. It would make a good video, IMHO.
My guess that I posted is that it vents from those rectangle holes at the bottom of the cap. The long and narrow paths eventually got clogged up. Ultrasonic will most likely clear it up.
I don't think it is ment to vent unless the pressure is high enough. (think pressure cooker or hot water tank) The cap is ment to keep the Ethanol under pressure to prevent it from evaporating. Just like the new gas cans.
@@MM-wt8oc How would it do that? Where is the pressure coming from? Are you saying when it runs the pressure will rise and then the cap will retain the pressure while it is in the garage over the winter?
The problem with such a design (assuming it's possible) is that if the tank holds pressure above 1atmosphere (only possible if it seals), then as the fuel drains while you are running it, air cannot get into the tank and if the pressure in the tank is lower than the pressure in the bowl, it won't flow. It's like when you dunk a straw in a soda and then cover the end of the straw and lift it out and the straw doesn't drain.
@@tarstarkusz he is saying when the pressure drops as the tank tries to provide fuel to the carburator and the cap does not vent creating a low presure in the tank, he also explained that it can cause issues if the tank gets warmer from winter to summer causing the tank to swell under extra pressure ((2 seperate issues from the same problem lol) this video actually solved an issue I was having with a generator (I didn't even think the small air his when I opened the cap was an issue, I was wrong lol)
I love seeing you torque every bolt with a torque wrench meanwhile I’m hitting them with my Milwaukee on low.
What you do is amazing. When I was a kid in school that was gonna be my career yeah, fix small engines, but my high school shop teacher told me don’t do it cuz there’s very little money in it.
I love the the thought process you use troubleshooting these kind of things. I probably would have just drilled a small hole in the old cap instead of buying one, but Im cheap like that.
Rance here Jim. What an astute observation ! But that’s what I have learned to expect, another very enjoyable and instructional video.
Here is why I really liked this one.
Many years ago (many, many), I had a British sports car. It had suffered minor body damage from a parallel parker, near the fuel filler. Picked it up from the body shop, and it died on me on the way home. I was mystified: the car had always run flawlessly, and the body repairs had nothing to do with anything under the hood. (Er, “bonnet.”) Before getting out tools (something one always carried with British cars) and fiddling with the carbs, I decided to smell the fuel in the tank. Spun off the cap and heard the air rushing in.
Left the cap off, drove to an auto parts store, bought a vented cap, and drove home no issue. Apparently the body shop had replaced the filler cap and, back then, one had to be sensitive to whether a given vehicle required a vented or unvented cap.
All that said, I got all the way through this video and never thought about the cap. Oh, well.
Good story.
I remember the metal caps with a vent hole. I miss those days. I still use my 1965 Briggs. I've replaced the rings once in 1988 or so. Did the valves too, since the head was off. Outside of replacing the rope a few times, never a problem. It was my grandparents mower. I keep the oil changed and run it empty every fall. It'll get passed on. Bad cap....that took some thinking cap. Great work.
Good leaning curve. We rarely asses a simple thing as a gas cap to be a problem, it is also an issue on cars once in a while. Thanks James.
I would never think to look for that.Nice catch.I really like those older flat head Briggs engines. Quantum and Classic.
Some times James things like that just slip's pass , no body at fault here, it is just one of those thing's. great catch thou, good video. keep up the good work.
Who would have thunk it? I love your videos. I've learned so much. Thank you!
I would have never guessed the CAP! Nice job Jim.
Yah, now I also need one of those fancy spark testers! A thing of beauty.
this is an unusual issue, you did very well to find it.
What a pain but a very good lesson to remember. Always check the simple things first which is sometimes hard to remember to do. Great diagnosis for sure. Thanks for the videos.
A fuel cap of all things those are just as bad as the spouts in fuel cans these days. Thanks for sharing your video James. Ed
Similar to an issue I had w my 40+ yr old Stihl chainsaw. Had me perplexed for a while.It came up when I serviced the saw and replaced the fuel and vent lines. To vent Stihl placed about a 1/8” set screw in the end of the vent tube. Thinking must’ve been that air could work its way past the threads but sawdust wouldn’t. Saw would start easily, run great for a minute or two but would starve and die. Finally figured out the new fuel line I’d installed was much more supple than the old and the set screw moulded to the line so no venting. Found small air filter like ends on the internet that push into the end of the vent line and ‘voila’ runs great. Never miss any of your vid’s.
Thanks Steve
I've been watching your channel for a while as I tinker with generator and lawnmower repairs, I've had a renegade generator sitting for a long time that had me stumped and had a lot of parts and effort put into it, I saw this video and took the cap off when testing it to find I had the same issue, it took longer to show due to the larger tank but after several runs that was indeed the issue, credit to you, an unsellable generator has now past its testing and been sold, your videos have helped on many occassions and it's appreciated
Nice
@@jcondon1 question for you, I delivered an 8kv generator to a friends farm where he was getting solar and batteries as back up which would also power pumps if needed, the electrician set the power of the solar to cut off the grid power I'm the event of a blackout and wired an earth to the frame of the generator and earth of the generator 240v plug and had it set up to run alongside the solar in the event of a blackout or fire, he just explained simply that this was so if their was a short the solar wouldn't be harmed, I didn't question him further as he was a little shirt on manners and busy, I am wondering if you could explain this in one of your videos, their are other videos about Wether to earth a generator or not (which was no help to this question and not clearly explained in layman's terms), just an idea, love the videos, so many helpful tips in assessing and repairing and much appreciated
Inside the bad cap is probably a valve, similar to the disk valve in a vehicle's radiator cap. That lets it build pressure to a certain level before releasing, but also allows a vacuum to open the valve. Gummy-goo ethanol gas glued the valve or it's holes shut, thus you had excessive pressure and no vacuum admittance. Let's have a cap deconstruction to see what's going on with the bugger 😉
The rubber gasket in cap rots and stopped up fuel supply
It’s really common so check inside cap for damage and replace it every 4/5 years for sure
I agree that sawing the cap in half, or less drastic action would be worthwhile.
Pretty simple and easy fix, that original cap could've been defective, nice work James!
I love your channel. I appreciate the fact that you make sure your torque pretty much every bolt to speck. In my opinion, it's important but not alot of other small engines mechanics just don't do it. Thank you James for sharing your skills with us.
Thanks.
I've never used a torque wrench. I just turn them 1/4 rotation before they break off. Ha ha
@@mtcman42
If it does snap off....just back it off 1/10 turn....
@justjeff4640 First tightening or turning a bolt eventually will create tension. The tension in the bolt provides the clamping force on the parts being held together. Not enough torque causes the clamping force to be insufficient, it vibrates loose when machine is used. Too much torque can strip threads and/or distort materials being joined.
Great Job finding that cap issue. You'll have it back soon because that pull cord is getting very thin and will soon snap.
Excellent job!
Thanks for these excellent videos! I've run into this twice on string trimmers. The first time you encounter this problem, you doubt your sanity because the engine appears to have everything it needs to run.
Another great instruction video my friend who would have thought that the filler cap was the problem thank you.
Wow, in all these years, I’ve never seen an issue like that with a mower gas cap. I’ve seen it plenty of times with portable outboard motor tanks that have a vent screw in the cap, but not those push mower caps. Great video as always!
Thank you for this one James. You certainly come up against some rare faults. I have seen you check gas tank fuel caps before if you suspect a possible airlock in the fuel system. This is the first time that I have seen you find one though. I must be cheaper than you because I would just have drilled a very small hole in the cap to allow the passage of air. A size 80 gauge drill bit with a diameter of 13.5 thou would be fine. It would have saved five dollars. Thats just me. I am sure that your approach is more professional.
A while back, I was given the exact same lawnmower with the exact same problem, and like James, I went through the same procedures until I found the problem. looking into the tank, I saw a very small white plastic tube in the intake and not knowing that it was some sort of filter, I pulled it out. Didn't fix the problem, but it ran with the cap off. Put the cap back on and engine quit a couple of minutes later. I pulled the fuel line off at the tank and no flow. Opened the cap to look in and gas started flowing. Put the cap on and it stopped. Upon examining the cap, I found no air vent hole, so I peeled back the little rubber gasket inside and drilled a .030 dia. hole thru the top of the cap and it ran fine. The other owner had taken it to two different shops, and they couldn't fix it. New air filter and blade sharpening and sold it for $120.00. Next time, I'll start with the cap. I would be worried about the "dished" cap letting water in. Where is the vent hole? Mine was domed.
@@mtcman42 Well it worked. You are right in worrying about the shape of the cap possibly letting water in. Choosing where to drill the hole then needs care. At the conclusion of James' video, his solution was to buy another cap with the vent hole designed into it. The designers of that cap obviously had the same problem to consider and must have acted on their view of it. It would be good to see the exact design of James' new cap as you say.
I decided to revisit the video. At 24 minutes in we can see the new cap as James looks at it. From there to 25 minutes James points to the hole in the cap. The top of that cap is definitely concave. That would certainly hold water. The hole is not at the bottom but some way up toward the rim. Perhaps to reduce the risk of water ingress. The diameter of the hole would influence the possible inflow of water. The bigger the hole the bigger the risk. I wonder what the size of the hole is in James new cap.
@@r8118830Water needs a larger hole than air. Drain holes for water are usually 5 mm. Air vents can be smaller. That said why not have a dome on cap? Many systems vent fuel tanks with a hose to the carb area, another proven design.
Unbelievable how you figured that out. I've been in that position but had absolutely no answer. I really appreciate you doing this 👍👏🏻👏🏻👏🏻😊
That's certainly amongst the LESS COMMON issues that turn up. It's nice that the outdoor temperatures helped by giving you an audio cue. That's certainly not the first thing you'd think of when you have an issue such as this. Vapor lock was one of my thoughts at the beginning, when I heard it "runs for awhile"...... so I was wasn't way on the moon with that idea.
I own a mower with a gas cap that has a deep vertical groove cut into the threads. I doubt it will ever fail venting. Any cap with a pinhole will sooner or later plug.
I really appreciate your videos. It gives me confidence I can keep my equipment running, because you describe in your videos the steps you go through when troubleshooting issues. I am also going to (not) read the comments until AFTER watching the video. It can be like reading the last chapter in a book first.
Great video , showed good trouble shooting methods . Also shows how one thing or system affects the other .This is hard to demonstrate in this field .Thanks again for taking the time .
Great diagnosis and easy to overlook. I had this same issue with a couple of older Honda HR214 mowers. Honda used a foam filter material inside their gas cap vent passage to keep dirt out (they still do). Unfortunately the old foam broke down and solidified over time blocking the vent and causing the engine to starve after about 10 minutes or so. I replaced the foam and they both ran great after that. Briggs also went through a few gas cap design changes in an attempt to “improve” things and they ended up with the horrible design they have now. It’s a half-turn cap that won’t stay tight, leaks fuel all over and traps grass clippings and dirt under the edge that fall into the tank when you open it. Simpler is better IMO, that cap you bought was always their best design.
Good win. Useful reminder that the cap must vent.
Great video James! Haven't seen a bad fuel cap in a long time.
James as always you have the golden touch.
My 1850 Colman Genorator was beginning to act up and after watching your post went and bought a new spark plug and it now runs better had an R in it and ran test and had very low omes.
But the gas tank cap was a home run and great to see that you were able to get it fixed that's something that I wouldn't have even give it a thought.
Good Job.
That was a curve ball (for me). Nice catch. Like the mix of machines you work on👍👍👍
Great video! I had the same issue and it took me forever to find the answer. I drilled a couple holes in the cap, and it fixed the issue. However, engine vibration caused gas to spray everywhere. I had to replace the cap anyway. Thanks!
Same problem brand new truck body builder had crushed the fuel tank breather hose against the chassis thanks for sharing James 🦘👍
Great detective work as always but an easy fix is only easy with hindsight.
No two items are exactly alike. Great channel. Great work ethic.
Go figure and the fact that he had to drive 3 hours to get it back to you! Process of elimination, works everytime. Congrats again.
Interesting set of issues and excellent detective work in solving all of them♥ Love watching and learning from your videos.
Thanks for this video which brings so much information that a ventilation in the cap is important. So: keep on mowing and always a sharp blade 👍🍀🌞😃
I sure learned something new today. I hope your friend isn't leaving that mower exposed to the elements. The cup shape of the top of the cap combined with a vent hole could spell trouble in the rain.
Nice catch! As you progressed through your problem solving approach, the cap was the last item on the list. Just goes to show that it's not a common problem, but not one to over look.
Jim, great find. My initial guess was a bad spark plug.
I had the same cap vent issue on a motorcycle. Tighten cap - stalled. Left cap loose ran like a champ. Replaced cap - no further worries. Great videos.
Thanks for a very interesting video. I will tuck that in my mind. About the time we figure out all the little tips, tricks, and traps to small engines everything will have gone electric!
Good analysis on this.
Great troubleshooting, but I think you should test further. You can test it my yard. Great vid, as always.
Great diagnosis and great video. Thanks for sharing.
Your videos on this specific mower has been very helpful because I have one of these very mowers, good job!
Had same issue with my B&S quantum. Replaced the cap with same one you did and fixed it. Same issue on our 25 year old snowblower with Tecumseh motor. New cap fixed that too.
Had that happen on my JD lawn tractor. After mowing for a while it would die and backfire and it would not start. I would go in the house for a while and it would restart only to do it again after a little while. When I figured it out I just pounded a nail through the hole that was supposed to vent and no more problems. That was 6 years ago and I'm still using that old tractor.
I never saw a Dremel wire brush before ! That's going on my shopping list ! Great video as usual. Thanks!
Jim: I do whatch your videls all the time and do all by own mower repairs. Put a new carb. on a Kohler engine. Engin ran too fast. Found interferance on large carb gasket. Cut a small piece out noy guns great when it starts. I am having the exact same problem. I have to use starter fluid to get it bto start. It does run but needs starter fluid fore every start. I was going to clean the new carberator but you may have saved me much time. Thank you.
Another top quality video. Thank you Donny. I have come across all these issues with customer machines. the vent problem happens a lot on Tecumseh snowblower caps that fall apart. No matter what machine, what works for me that I advise all my customers to do is keep the fuel tanks completely full at ALL TIMES with premium. Any container left in temperature change will get condensation resulting in water in the carburetor. If the machine has a shut off fuel valve I turn off the fuel and run it till it quits before storage.
I have one of those mowers that does something very similar. I will have to try a new plug and a new fuel cap. The carb is good, so I guess that's my next step. Thanks for posting this.
I knew you could get it running properly! Easy fix.
Nice episode. Had a snowblower that would do the same.
Another truly fine bit of detective work James. I've had this problem in the past; it can be a real toughie to figure out. Thanks again for another fine video. God bless. Rev. D.
That's why I finally switched to a battery mower.... Still love my gas backpack blower for the ton of leaves we get in fall but every week mowing is now quiet and reliable....and way less stinky. As soon as good blowers are available in battery I'm switching. But you can take my 2 stage gas snowblower out of my cold dead hands. I live in MN....
The engiine looks like a newer version of the Briggs 4.5 Quantum.
My mother bought a new TORO GTS2 back in June, 1995.
It has a 4.5 Quantum on it too.
My mom passed away in Sep 2020, but I still have that old mower, and it still runs. It got a small piece of plastic or crud stuck in the carb back in May-June of 2005. A carb rebuild kit & cleaning fixed it. It got dirt in it once after that, so I knew what to do.
It doesn't have very good compression, after all these years now.
But I still use it a few times a year to mow part of a shooting range target area about 12 miles from me. It still gets the job done. I also have TWO spare identical used engiines that also run. When the current engiine shits-the-bed, I will swap out the engiine.
I love your videos. I will never fast forward thru any part of your videos for fear of missing something. I can't say that about many other videos. I had a Troybuilt with the same problem. Drove me crazy until I finally figured it out. Because I had this problem, I suspected that that might be your problem.
The vent on my riding mower slowly got clogged over time unbeknownst to me and caused the same issue. The darn thing would run for 20 minutes that way and slowly lean out! Once I discovered the blocked vent on the fuel cap, loosening it solved the problem, but not before numerous carb cleanings, carb kits and tank cleanings! This had been going on for a couple years, and exhibit itself on hot days too!
Ahh, I have seen that before on a tiller engine ..Good detective work James ! ENJOYED..
Got one like that, but It has the good cap. At times I have some troubles with the kill handle....sometimes I have to pull harder on the cable. Thanks for the nice video, very helping.
Well done James, your friend will be delighted. But a 3 hour drive to deliver it, it might be cheaper to send it by courier - the price of fuel these days. Thanks for sharing
Hi James very entertaining video mate you have the patience of a saint great detective work finding the fault
Thanks Dean!!
Wow nice find on the Gas tank Cap
@16:00 you were testing fuel flow, I grabbed a cigarette to smoke, but quickly returned the lighter before igniting it fearing the vapor of the fuel to burn.
Then I remembered it was only a video 😁
I was hoping you were going to take apart the old cap to figure out how and why it wasn't venting properly. May just have dirt in it and needed to be soaked or cleaned. Great video!
Who would've thunk it? Great fix!
Nice save James
Good detective work, James!
wow, never would have thought that was the issue... that's why we go to the pros... thx!
You are very good at fault finding, i guess we don't see the time duration but regardless you always get to the bottom of every problem.
Thanks, James. I already knew about the failed fuel cap check valve syndrome, but hadn’t seen one of those DIY fuel drain hoses. Just made myself up one and put a length of duct tape around it so there’s no mistaking it’s a tool. I may hose clamp on some sort of wire eye with which to hang it up near my fuel containers. 👍🔧🧰
If I am not mistaken most caps are designed to hold pressure to keep the fumes in the tank for EPA/CARB compliance. They also have a one-way valve to prevent vacuum in the tank. Had a pressure washer that did the same thing as this mower. The cap on the tank was able to be disassembled and I found the valve to be similar to a MTD 2 stroke fuel cap. the ones with the little slotted rubber nipple for the valve.
I had a similar behaviour on my Toro, eventually I found out that the auto choke was broken. I changed the auto choke and since then the machine works flawlessly.
Gas caps are something that can be easily overlooked and that have a big influence on small engine performance. Maybe something to be added to your future list of things to check.
I’m having a similar loss of power in my Troy Built with a Honda engine push mower which is becoming more difficult to start. I’ve put in fresh gas, Octane 94, a new NGK spark plug OEM, replaced the air filter, changed the oil, but tipped it once on the wrong side. I’m still puzzled so far. Thank you for your excellent video and diagnosis!
A faulty gas cap! Nice catch figuring that out. Well done! I'm subbed now! 👏
I do the same line of thought,,I usually cut my lawn several times b4 listing it if there's an issue you hope it shows up while in your control.
The original cap is known to go bad. Probably some emissions garbage. Anyway I took one apart a long time back and I believe it has 2 spring loaded plastic valves in it.
With the cap you added I will recommend a in-line fuel filter and tell your buddy do not leave it outside. Water will get into the tank. Nice find btw.
I bought a funnel that filters out the water, you might find one to be useful, enjoy your videos
I think the reason there are 2 very different fuel caps listed for this engine is that the original cap is required to meet EPA clean air requirements mostly for the state of California the replacement cap is a noncompliant version.
Walt
You are so thorough best on the internet
15:38 My first thought was: that's pretty little fuel flow.
I did not see that fuel cap thing coming,, my money was on the autochoke..
The replacement cap you got is the exact cap that my 2009 personal pace came with and is still on it...
Some lawn unit have that feature,you tighten the cap for transportation and release it to unvent It when you start it the tank.