A couple of posters have told you that the coil is likely to be the problem. I agree. Coils typically fail initially when they get hot. Over time they fail completely. Rivets gave you the procedure for ruling out a failing coil. When you can’t restart a hot engine, that’s when you test for spark. Either buy a cheap inline spark tester (like $5-6 at Tractor Supply) or you pull the plug and ground it against the engine and see if you have spark. If you get spark when hot, rule out the coil and look for a fuel problem. If you get no spark when hot, that means you buy a new coil. Rivets also gave you the procedure for gapping the coil. Some of the pros here tell you to avoid cheap after market parts. If I were warranting work like they do, I would do the same. But if you are working on your own mower then I would buy a cheap coil from Amazon and if it didn’t work, return it and spin the wheel again. Time is not money for us retired folk. Good luck. The coil is low hanging fruit, go there before worrying about valves.
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John Deere JS38 push mower
- Thread starter dannac
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Export threadYes I did ... and #31 I asked if that would stop it from starting even though the spark plug had spark ... but got no reply to that question.Yes. Did you read and follow post #30?
Thanks
Thank you .... will put it back together.A couple of posters have told you that the coil is likely to be the problem. I agree. Coils typically fail initially when they get hot. Over time they fail completely. Rivets gave you the procedure for ruling out a failing coil. When you can’t restart a hot engine, that’s when you test for spark. Either buy a cheap inline spark tester (like $5-6 at Tractor Supply) or you pull the plug and ground it against the engine and see if you have spark. If you get spark when hot, rule out the coil and look for a fuel problem. If you get no spark when hot, that means you buy a new coil. Rivets also gave you the procedure for gapping the coil. Some of the pros here tell you to avoid cheap after market parts. If I were warranting work like they do, I would do the same. But if you are working on your own mower then I would buy a cheap coil from Amazon and if it didn’t work, return it and spin the wheel again. Time is not money for us retired folk. Good luck. The coil is low hanging fruit, go there before worrying about valves.
You are going to hate me after reading this post, but you won’t be the first to do so. If you understand my post on resetting the air gap you would realize that the answer to that question was answered, as this would mean you need the proper gap on both legs of the magneto. With your lack of knowledge of how engines work, I would not recommend cleaning the piston, valves or cylinder. Could do more harm than good. I’m getting frustrated as at this point I don’t think you will solve this problem because you keep jumping around as to what you should do. This thread has covered the ignition system, fuel system and compression system, but at this point you’ve never completed diagnosing any one of those systems before jumping to another one. That is why you are getting confused and confusing those who are trying to help you. Troubleshooting small engines means to go in one direction and ruling it out before going another direction. My recommendation at this point is get a new head gasket and reassemble the engine. Then test the unit. If it is still a no go, start by troubleshooting the ignition system unit you get spark, then go after the fuel system and finally look at the compression system. Unless you use a step by step troubleshooting procedure you’ll never solve the problem unless you get very lucky. Probably my last post here until I see a more direct route on your part. Once again read my signature, as you may agree with others that I only know book knowledge and it’s time to start ignoring me. Sorry!!!
Beings I had it apart and easy access now ... just wanted to know if I should try to clean it ... that's all.You are going to hate me after reading this post, but you won’t be the first to do so. If you understand my post on resetting the air gap you would realize that the answer to that question was answered, as this would mean you need the proper gap on both legs of the magneto. With your lack of knowledge of how engines work, I would not recommend cleaning the piston, valves or cylinder. Could do more harm than good. I’m getting frustrated as at this point I don’t think you will solve this problem because you keep jumping around as to what you should do. This thread has covered the ignition system, fuel system and compression system, but at this point you’ve never completed diagnosing any one of those systems before jumping to another one. That is why you are getting confused and confusing those who are trying to help you. Troubleshooting small engines means to go in one direction and ruling it out before going another direction. My recommendation at this point is get a new head gasket and reassemble the engine. Then test the unit. If it is still a no go, start by troubleshooting the ignition system unit you get spark, then go after the fuel system and finally look at the compression system. Unless you use a step by step troubleshooting procedure you’ll never solve the problem unless you get very lucky. Probably my last post here until I see a more direct route on your part. Once again read my signature, as you may agree with others that I only know book knowledge and it’s time to start ignoring me. Sorry!!!
I've cleaned all other parts I've taken apart, so thought to check if I should clean piston / valves.
Not jumping around are looking for something new to try.
I got it ... with the engine I have a valve adjustment is over my head and do not want to try.
Putting it back together ... will not clean or mess with piston or valves.
Though may take me s day or two.
I appreciate your reply.
Last edited:
Installed coil using business card as mentioned. Everything in place except spark plug.
Set spark plug against engine, held the kill switch bar in normal run position, and spark plug has immediate fire when pulling the cord.
Installed spark plug and put a little gas in tank and gave 7 or 8 pulls. Not a hint of wanting to start.
Any other ideas ... I'm willing to try.
Set spark plug against engine, held the kill switch bar in normal run position, and spark plug has immediate fire when pulling the cord.
Installed spark plug and put a little gas in tank and gave 7 or 8 pulls. Not a hint of wanting to start.
Any other ideas ... I'm willing to try.
I would take off the air filter and spray carb cleaner or starting fluid into the carburetor. Then try to start it. If it starts and then quits, you have a fuel delivery problem. If it does not start, then you have either a compression problem or an ignition timing problem. Ignition timing is easier to fix than compression, so that’s where I’d go after eliminating the possibility of a fuel problem. As Rivets has alluded, you can rule in or rule out an ignition timing problem by examining the flywheel for a sheared or deformed key.Installed coil using business card as mentioned. Everything in place except spark plug.
Set spark plug against engine, held the kill switch bar in normal run position, and spark plug has immediate fire when pulling the cord.
Installed spark plug and put a little gas in tank and gave 7 or 8 pulls. Not a hint of wanting to start.
Any other ideas ... I'm willing to try.
Nov 10, 2023
7 pulls ... no hint of starting. Pulled plug, seemed dry.
Purchased a carb cleaner spray.
Removed air filter and gave a good spray. Almost started 1st pull but started 2nd pull.
Let it run approx 1 minute and I shut it down.
Quickly noticed smoke coming from engine towards top. Not lots of smoke, but yeah smoke.
Pulled off top plastic cover, but could not tell exactly where the smoke was coming from, as it seemed to be from under the metal cover.
Let it sit about 5 minutes.
Then tried to start it again ... 3 pulls, no hint of starting.
7 pulls ... no hint of starting. Pulled plug, seemed dry.
Purchased a carb cleaner spray.
Removed air filter and gave a good spray. Almost started 1st pull but started 2nd pull.
Let it run approx 1 minute and I shut it down.
Quickly noticed smoke coming from engine towards top. Not lots of smoke, but yeah smoke.
Pulled off top plastic cover, but could not tell exactly where the smoke was coming from, as it seemed to be from under the metal cover.
Let it sit about 5 minutes.
Then tried to start it again ... 3 pulls, no hint of starting.