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Hi hoping someone can help me. Ok. I have a John Deere 318. Starts fine runs great. But 15 minutes in shuts down. Ok. This is where I get lost. Trying to start it over and over again nothing. Now with a test light on the negative side of the battery in the other end on the coil both wire lead to the coil have power when the key is on if I turn the key on and off and hitting the starter a few times as the second wire lead loses power it’ll fire right up Run for almost an hour And then shut down again use the test late again once the far side goes out again it’ll fire up and run all night all day then I have to do this again when it’s time to cut the grass over and over I’m not sure if it’s the coil and it’s almost $300 for a coil.. replace the key switch any help on my issue thank you
 

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Is your engine a p218 or b43?

Either way, the condenser is probably the issue, it’s under $20.

If that doesn’t fix it you can get an aftermarket Harley coil for cheap money.

If it’s a p-218 it might be the magnetic pickup, but that’s still under $100.


Bottom line, I would throw a condenser at it, and then you can test your way to the problem part at a reasonable amount.
 

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If your more interested in learning to fish, first you want to create a free account at JDparts, and second look up the part numbers that are HE111-1111.......drop the HE and the JD part number magically becomes an Onan part number. That saves a lot, things like the Harley coil compatibility saves more.
 

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Discussion Starter #4
Is your engine a p218 or b43?

Either way, the condenser is probably the issue, it’s under $20.

If that doesn’t fix it you can get an aftermarket Harley coil for cheap money.

If it’s a p-218 it might be the magnetic pickup, but that’s still under $100.


Bottom line, I would throw a condenser at it, and then you can test your way to the problem part at a reasonable amount.
Thanks I’ll try that. Cheers
 

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Moggy, the 318 you have has the P218G Onan engine (from pic you provided) which has the electronic ignition module and ring under the fly wheel. They are heat sensitive. The condenser should be hooked to the positive of the coil. The old mechanical points engine (B43) has the condenser hooked to the negative of the coil. I would check for spark right after it shuts down. That will help us out greatly to pinpoint the problem and save you money.
 

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Discussion Starter #6
Moggy, the 318 you have has the P218G Onan engine (from pic you provided) which has the electronic ignition module and ring under the fly wheel. They are heat sensitive. The condenser should be hooked to the positive of the coil. The old mechanical points engine (B43) has the condenser hooked to the negative of the coil. I would check for spark right after it shuts down. That will help us out greatly to pinpoint the problem and save you money.
Ya when it shuts down it has no spark but sometime not always when turning the key off and on without Turing it to the start it will backfire. Got me going crazy. Cheers
 

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James,

This is further evidence that the module behind the flywheel is likely the root cause -- when the key is turned off the magnetic field collapses in the ignition coil the same way as if the module had properly switched the current off at the correct crank rotation. Since the crank is not necessarily in the top of stroke position, a backfire is a likely consequence.

Attached is how to test the module with a meter prior to removing the flywheel and replacing it.

Chuck
 

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And here is what the module looks like behind the stator under the flywheel...
Onan ingition module.JPG


Let me know if you have other questions...

Chuck
 
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