# Onan P218G pump & module questions



## mmarcon (Jul 19, 2016)

Hello all! Writing to ask some questions.

I hope that I've correctly begun a thread to ask these questions.

I'm in the process of bringing a JD 318 with a Onan P218G engine back to life. I'm an old aircraft mechanic but do not quite understand some things about this engine.

1. It has a three port pulse fuel pump on it. On top, are "In" and "Out" ports. On the bottom is a single port marked "In." I can find no evidence that the bottom, or I suppose, crankcase pressure port, has ever been in use. (Engine has 1300+ hours on it.) The top "out" port hose goes to the base on the carb throat at the manifold. Do I assume correctly that the pump operates on "pull" vacuum from there and doesn't require a crankcase push?

2. What are the "Time Delay Module" functions on this tractor? Although I've had some starting problems in the past, mainly due to a wire break, I've never had a high temp shut down, even on the hottest days and the hardest operation with this engine. In fact, for the last several years, because I forgot to plug it back in, the seat safety switch has never inhibited the engine operation. How integral or important is the modules presence to the basic "ignition-fuel-air-fire" operation of this engine?

Thanks in advance for your help. Mike


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