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Discussion Starter #1
I have a 318 with a Onan p218 engine that has just started running rough (hunting). However, it runs fine when mowing. Last week it was fine, this week it started hunting. I thought it was the governor but after about 10 min. of mowing the battery light comes on. I'm starting to think it's an electrical problem. It has new plugs, new gas filter and Ive put Seafoam through it with no change. I'm OK with mechanical problems, but I get lost when it's electrical. Any suggestions?
Thanks
 

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Sounds like it could be two separate issues... The engine surging and hunting (particularly at low speeds and no load) would indicate either a clogged low speed jet i the carburetor, or an air leak in the manifold. There are many threads on WFM and a few on this forum about re-sealing the split manifold on the Onan engine.

The battery light coming on after a few minutes of operation with the PTO engaged could be a PTO winding with a partial internal short...the DC resistance of the clutch coil should be in the range of 3.4 to 4.9 ohms. If it is substantially lower, you may be draining the battery. Does this symptom occur if you do not use the PTO? If only when using the PTO, start by measuring the resistance. IF the symptom occurs with the PTO off, look into the voltage regulator or the condition of the wiring and connectors in the charging circuit.

Chuck
 

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Discussion Starter #3
manifold propane test

I'm confused about the manifold propane test. What is supposed to happen when using an unlit propane torch at the manifold? I'm assuming that you "play" the torch all around the seam, correct? Then what happens?
 

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It will draw the propane in and change the RPMs of the motor slightly. You will be able to hear the difference if you have a leak.
 
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