Just found a dead cylinder on a GX620. Was trying to find out if the stop diode could cause a no fire issue on an individual cylinder. Thank you for the video. You might want to consider a TA100 SmarTach+. With it you can read min/max voltage as well as RPM without having to pull a plug wire which would prevent false diagnosis with a plug tester.
Thanks for the vid, this might be whats wrong with mine. Better this than a push rod. I would have never would have thought of this with a spark on both sides. Thanks for taking the time to post!!
I'm chasing a low power issue today. Did notice my engine has the swirl or blowey thing that keeps the cylinders cooling fins clean. B&S also provides flaps to inspect these areas.
It is the yellow wire running from the regulator, connecting to the black wire through a diode. The black wire is frayed and obviously became disconnected from wear. I don't know where to reconnect it. It could be in the harness but I don't see any broken wires in there.
Got a 100 series John Deere with a twin cylinder engine that looks a lot like this. Google got me here as I have a similar issue No spark on one cylinder. The mice have been nesting under the cover and I suspect a wiring problem. Always like to get a heads up with a UA-cam video if I can find one before I tear into an unfamiliar engine. Good video to get me informed on what's under the cover. Wasn't aware diodes could be a potential problem. Guessing mine has mouse bite issues. LoL Thanks for the info.
Exactly the same harness was chewed up. 5 inches of bare wire on one wire 2 inches on another. Electrical tape temporarily insulating wires until I get a new harness.
@@Wrenchesandrods Probably save a few bucks that way. Thought about using a metal fuel or brake line for conduit to mouse proof it. LoL Maybe foil tape.
Thank you for the video. Opens up some ideas for me to check. My engine has a similar runability problem. Also somebody added a push button start to my mower and still has a key switch also. I keep burning up the button switches. I found a from the starter solenoid going directly to the starter going directly to the starter. There is also a wire from the starter to the button switch. Does that seem right? I feel that is sending current to the button and buring it out. What are your thoughts?
I have the same problem ( I think) 1 pursuing firing however exhaust coming out the intake AND the mower deck appears to run backwards when I engage the deck clutch!
Deleted my diodes.. Engine runs great. takes 15 seconds to shut down after I turn key off. Not charging when running so I keep a small solar panel attached to the battery when it's not running.
What you are measuring is Forward and Reverse resistance in Ohms, not voltage, The voltage from the meter provides bias to either forward or reverse the diode junction (depending on the polarity of the meter probes) providing the two resistance readings. That's probably more info than anyone wants to know, but I'm too anal to have let it go. Good diagnostic video otherwise!
Im gunna bet this is whats going on with mine...one plug fouls out ..iv changed coils around,cleaned card..no difference..im gunna check this..il bet thats the fix...😎👍💯..i will subscribe..good information...
With the wire hooked up to the coils and the plug unplugged, should there be continuity from the terminal on the coil to ground? Great video! I learned my new thing for the day. Lets go for another.
Like the video and process... haven't seen this issue yet... wondering would it be a good way to test kill wires and diodes to unplug both wires, crank it up? To shut it back off after simply crimp the fuel line to shut down?
I don't think so. When the diode goes bad, it allows current in both directions, which makes it spark out of time. It's still sparking, but it's just at the wrong time.
My engine is running fine. There is a red wire and a yellow wire running from the regulator. The red powers the auxiliary light, the yellow went through a diode to a black wire that became disconnected and is loose. The lights no longer work so I assume this black wire is the reason. Can someone help me identify where the black wire is supposed to connect?
@@Wrenchesandrods oh my goodness, thank you for responding so fast. No, you are correct. It has two cylinders. Does it have two coils or one? I’m having the same issue as the title of your video Another video showed one coil, two cylinders with one misfiring cylinder I can see two coils in your video at the 15 minute mark overhead view of your engine. Mine must have two coils so I could swap them from one side to another to see if it makes a difference. Once I do this I'll investigate the diodes. Already took carb apart and cleaned it. Thank you. Thumbs up!
@user-ik4fd9ny4b pull the kill wires off of your coils and see if the spark returns. If it does, you might have a bare spot on one of your kill wires that is grounding to the block, or one of the diodes is bad.
@@Wrenchesandrods I did have a bare spot.. MiCE! Also, the coil was nearly touching the wheel, maybe 3 or 4 thousands. Could/would that interfere or stop sparking?
For me both cylinders are firing but the “driver side” one isn’t firing as much as the other side and i can’t figure out why for the life of me, i’ve tried everything i can think off and it doesn’t seem to want to work properly, both fire but one is not firing as much
@Wrenchesandrods I'm not the original owner, and my dad had this mower sitting around for 5+ years. I think the oil has been barely changed or not at all. It also doesn't have an oil filter. I think small metal shaving had gotten in between the connecting rod and crank shaft, causing increased friction and heat. The cylinder is fine, so I'll rebuild it. I need to clean off the welded aluminum on the crankshaft and polish it. Other than that, it really only needs a new rod and piston.
MY daddy would have whipped my butt if I didn't clean that engine off when I was done fix'n it...All that dirt on them cylinder heads can cause overheating and bad things can happen to that sweet old engine....Great diagnosis though,,!!!!👍
Sure just starve it of gas and it'll shut off or choke the air breather or leave your kill wire plugged to the coil and unplug it from the harness let it dangle touch it to any metal to shut the mower off
Very methodical diagnosis!! Great catch man!
Thanks Brad! I appreciate that!
Just found a dead cylinder on a GX620. Was trying to find out if the stop diode could cause a no fire issue on an individual cylinder. Thank you for the video. You might want to consider a TA100 SmarTach+. With it you can read min/max voltage as well as RPM without having to pull a plug wire which would prevent false diagnosis with a plug tester.
Great video! That’s a hard one to trace as most people would see spark and think good!
Thank you. I appreciate your kind words!
Thanks for the video! I’ve got a snapper with a very similar motor, single cylinder fire. You might have just saved me a lot of time!
@@MikeysXS that’s why I make these videos!!! You’re welcome
You sir, are a genius! I did not realize the harness contained diodes. Simple fix. Thank you!
@@kentait7153 thank you! I'm glad I could help!
Chased this issue for two days, this video got me to the problem. Thank you. Well done!
Thank you! Be sure and subscribe!
2:24 Wow, your valve cover came right off! Mine was glued with sealant, I’m guessing someone worked on it before now😁
Great trouble shooting! Thanks for sharing the knowledge and experience. God Bless you and your business!
Thanks for the vid, this might be whats wrong with mine. Better this than a push rod. I would have never would have thought of this with a spark on both sides. Thanks for taking the time to post!!
This was exactly the problem I had. Many, many thanks for posting this repair.
Your welcome
My 18hp Briggs and Stratton V Twin is acting the same way. Great troubleshooting. Ill dig into it tomorrow . Ive liked and subscribed!
@@michaelhouy1382 thank you!
Thanks for the video, helped me a lot, especially tell that you still have spark, but you still have a problem.
@jeffreyarnold5278 thank you
I'm chasing a low power issue today. Did notice my engine has the swirl or blowey thing that keeps the cylinders cooling fins clean. B&S also provides flaps to inspect these areas.
It is the yellow wire running from the regulator, connecting to the black wire through a diode. The black wire is frayed and obviously became disconnected from wear. I don't know where to reconnect it. It could be in the harness but I don't see any broken wires in there.
@@TomDebalsi-y6f the yellow wires should got to the alternator/stator
Thanks for video. Time to troubleshoot.
That was awesome I've seen that before but forgotten about it thanks for the info 😅
I have a 22hp BS running on one cylinder so i will go through that process and see if it works. Thanks for this video.
You're welcome!
Yes. The new diodes fixed it right up!
@JEFFQUICKLE9 not that I know of, but you can order them on Amazon
My problem is not the diodes. I checked them and they are good. Put new coils and plugs on and still down one cylinder.
@@Twohandsranch58 do you have compression in that cyinder?
Great diagnosis
@@MikeKlinkner thank you
Didn’t have the same problem, but this really helped me. Thank you so much.
Thanks for the positive comment!
This was so very helpful!
@@gregpendleton4957 thank you
Thank you for this content!
You're welcome
Got a 100 series John Deere with a twin cylinder engine that looks a lot like this. Google got me here as I have a similar issue No spark on one cylinder. The mice have been nesting under the cover and I suspect a wiring problem. Always like to get a heads up with a UA-cam video if I can find one before I tear into an unfamiliar engine. Good video to get me informed on what's under the cover. Wasn't aware diodes could be a potential problem. Guessing mine has mouse bite issues. LoL
Thanks for the info.
@googleuser868 check your kill wires. If they are chewed, they will ground on the engine and kill your spark
@@Wrenchesandrods Will do. Hoping it's something real easy like that.
Exactly the same harness was chewed up. 5 inches of bare wire on one wire 2 inches on another. Electrical tape temporarily insulating wires until I get a new harness.
@googleuser868 I rarely replace the harness. I'll replace wire and heat shrink it
@@Wrenchesandrods Probably save a few bucks that way. Thought about using a metal fuel or brake line for conduit to mouse proof it. LoL
Maybe foil tape.
Good catch. I see these engines with cracked intake manifolds also causing dead cylinder.
Thank you! I have not seen one with a bad intake cause a miss yet! Thanks for sharing! I'll put that in the ol brain for later diagnosis'
The plastic ones can crack
Thank you for the video. Opens up some ideas for me to check. My engine has a similar runability problem. Also somebody added a push button start to my mower and still has a key switch also. I keep burning up the button switches. I found a from the starter solenoid going directly to the starter going directly to the starter. There is also a wire from the starter to the button switch. Does that seem right? I feel that is sending current to the button and buring it out. What are your thoughts?
@@rickpendleton7036I'd wiring a solenoid back up
Great job!!! I think I'm chasing one of these issues.
Thank you!
Thanks, good trouble shoot
First thing to check if the plug is wet is to check for sparks
I bought a pack of 125 of those diodes for $8.00 online. Been using them for years.
Thank You!
I have the same problem ( I think) 1 pursuing firing however exhaust coming out the intake AND the mower deck appears to run backwards when I engage the deck clutch!
Deleted my diodes.. Engine runs great. takes 15 seconds to shut down after I turn key off. Not charging when running so I keep a small solar panel attached to the battery when it's not running.
What you are measuring is Forward and Reverse resistance in Ohms, not voltage, The voltage from the meter provides bias to either forward or reverse the diode junction (depending on the polarity of the meter probes) providing the two resistance readings. That's probably more info than anyone wants to know, but I'm too anal to have let it go. Good diagnostic video otherwise!
nice video and test. keep it up.
Thank you! I really appreciate comments like this!
Nice job. 👍👍
Im gunna bet this is whats going on with mine...one plug fouls out ..iv changed coils around,cleaned card..no difference..im gunna check this..il bet thats the fix...😎👍💯..i will subscribe..good information...
When I see a new coil on that cylinder I AllWAYS pull the kill wire to check dio on b/s twin
With the wire hooked up to the coils and the plug unplugged, should there be continuity from the terminal on the coil to ground?
Great video!
I learned my new thing for the day. Lets go for another.
With a bad diode, yes. With a good diode no
Awesome👍
Damn that black tool box looks familiar!!! 🤣🤣🤣🤣🤣🤣
Hell yeah it does! I'd rather him be using it still though!
Built to fail. Not like the old days of a briggs engine. Good work!
Like the video and process... haven't seen this issue yet... wondering would it be a good way to test kill wires and diodes to unplug both wires, crank it up? To shut it back off after simply crimp the fuel line to shut down?
I don't think so. When the diode goes bad, it allows current in both directions, which makes it spark out of time. It's still sparking, but it's just at the wrong time.
If the diodes are bad it can still have spark on both cylinders?
@@LSCentral5328 yes the will spark at the same time making one of the spark at the wrong time.
How about the size of the diode ???
Don’t want to buy the wire harness 😊
Thanks for sharing and any part information possible
amzn.to/3Pe853v Here is an Amazon link to the whole wire.
$12 for two of them makes it worth ordering just to have it on hand.
@@markchidester6239I agree and did that and in a week used one
Thanks
It’s just a one way valve is all
Simple as that 😮
Perfect
My engine is running fine. There is a red wire and a yellow wire running from the regulator. The red powers the auxiliary light, the yellow went through a diode to a black wire that became disconnected and is loose. The lights no longer work so I assume this black wire is the reason. Can someone help me identify where the black wire is supposed to connect?
If it’s the black wire running to the coils it will go from the coils to the harness
Your at over 1,300 subs now, great...this video did it..great finding the issue..il bet everyone having this issue subbed like i did...😎👍💯
Thanks!
@@Wrenchesandrods you bet...😎👍💯👋
Mines the same engine except for the air filter cover is different mine doesn't screw on it has the yellow piece you undo mine is 40h777
I have a question? If a 24HP Intel only has one coil (and it's bad) how can one cylinder have spark and the other doesn't?
I've never seen a 24hp intek with only one cylinder to my knowledge
@@Wrenchesandrods oh my goodness, thank you for responding so fast. No, you are correct. It has two cylinders. Does it have two coils or one? I’m having the same issue as the title of your video
Another video showed one coil, two cylinders with one misfiring cylinder
I can see two coils in your video at the 15 minute mark overhead view of your engine. Mine must have two coils so I could swap them from one side to another to see if it makes a difference. Once I do this I'll investigate the diodes. Already took carb apart and cleaned it.
Thank you. Thumbs up!
@user-ik4fd9ny4b pull the kill wires off of your coils and see if the spark returns. If it does, you might have a bare spot on one of your kill wires that is grounding to the block, or one of the diodes is bad.
@@Wrenchesandrods I did have a bare spot.. MiCE! Also, the coil was nearly touching the wheel, maybe 3 or 4 thousands. Could/would that interfere or stop sparking?
@@L46C3 use a business card to gape the coil to the magnetic and you should be set!
I don't have a spare mower lying around, any idea where I might get that wire with the diodes?
Amazon
Most repair shops keep them in stock 😊😊😊
For me both cylinders are firing but the “driver side” one isn’t firing as much as the other side and i can’t figure out why for the life of me, i’ve tried everything i can think off and it doesn’t seem to want to work properly, both fire but one is not firing as much
Pull your kill wire off the weak coil and see if the spark improves. If it does, you kill wire is grounding to the block somewhere.
It could be a to tight valve
It’s just a one way valve folks 😢
Where did you get that fancy compression tester?
My mom made it! It took about 9 months!
@@Wrenchesandrodslolol 😮
Mine had a blown rod 😅.
It happens a lot. Did you run it a little low on oil.
@Wrenchesandrods I'm not the original owner, and my dad had this mower sitting around for 5+ years. I think the oil has been barely changed or not at all. It also doesn't have an oil filter. I think small metal shaving had gotten in between the connecting rod and crank shaft, causing increased friction and heat. The cylinder is fine, so I'll rebuild it. I need to clean off the welded aluminum on the crankshaft and polish it. Other than that, it really only needs a new rod and piston.
Good vedios
MY daddy would have whipped my butt if I didn't clean that engine off when I was done fix'n it...All that dirt on them cylinder heads can cause overheating and bad things can happen to that sweet old engine....Great diagnosis though,,!!!!👍
Everything gets a bath before it goes back home to the customer.
I can see your dedication and common sense. World needs more mechanics like you, have any experience working on Boeing 777's. LoL
@@timmythepilot negative 🤣🤣🤣🤣
Mine tells me to get rid of some of my mowers i have but then always get more for free and buy a few more
Could I just run the engine without the coil safety ground wire? Theoretically of course
Yes, but you won't be able to shut it off
Sure just starve it of gas and it'll shut off or choke the air breather or leave your kill wire plugged to the coil and unplug it from the harness let it dangle touch it to any metal to shut the mower off
I know one man who ran a wire just to kill it until I told him what was wrong and I had the part 😊