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Koobs

My Onan 18 only starts in “run”

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Koobs

When I turn the key on my 518H, it will crank over all day but will not start. Then, when I let go of the key and it slips back to “run” position of the ignition, it will try to fire (gets spark), and with some practice I can get it to run. Once it fires up, it runs like a champ. Something is wrong with the “start” Circuit. I need some help?? Thank you guys in advance. 

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gwest_ca

Welcome to the forum.

The first thing I would do is check the function of the switch. Sounds like it is failing to power the I (eye) terminal with key in start position. Very common switch.

Click on the picture for the procedure

Garry

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Stepney

Yep, it's your switch. My 516-H was just the same. Let go of the key and it'd catch if you were lucky. Mine was beat to an inch of its life so it simply had a jumper wire from the coil to the battery. New switch should have you going reliably again!

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SylvanLakeWH

And...

 

:text-welcomeconfetti:

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953 nut

:WRS:

As Garry said, ignition switch has seen better days. 103 990 switch should be available at auto supply stores or on :techie-ebay:

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Koobs

I replaced the ignition switch, and that didn’t help. I should of mentioned that. I tested the terminals in the different positions, and the new switch functioned properly. Any other ideas guys? 

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Bill D

Check the 9 pin connector for burnt pind.  If it looks okay clean all the terminals and reassemble with dielectric grease on all pins.  Bill

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Koobs

Thanks, I’ll try that. 

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lynnmor

Your tractor has several relays that control the ignition, if one of these are bad it might be your problem.  Download the demystification guide and check the circuits pertaining to starting and ignition.  

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gwest_ca

Garry

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gwest_ca

If the ignition switch is working properly the ignition power from the ignition switch is the same in START and RUN.

 

Garry

 

 

p7-121 1988-89 518 520 Spark.jpg

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