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Suave 05-16-2011 09:33 AM

Yanmar 2GM20F
My boating partner had posted our difficulties priming the secondary fuel filter etc. The trick was turning the crankshaft: once we did that, the mechanical fuel pump worked like a charm. We cleared the fuel filter, the lines at the fuel injector etc and all worked fine. Thanks so much.

The engine started right up. However...while the engine was idling, the engine would rev up, rev down, without me operating the throttle. It had done this once before...We spoke to our mechanic who inspected the engine. He said that sometimes the mechanical fuel pump diaphragm gets a hole and you end up getting diesel in the engine. He said he had heard some engines then could not be killed. He also said that it looked like we had overfilled engine with oil, but that could have been caused by diesel getting into he oil.

When we went to check out the engine, there was diesel (appearing diluted) pooled under the engine with what looked like pieces of oil in it.

Would appreciate your input. The posting on the forums have been extremely useful. Happy sailing. We hope on getting out there soon.


arf145 05-16-2011 10:10 AM

Carlos, others can comment on fuel getting into the engine through the lift pump--I don't know about that. But I do know that the lift pump doesn't last forever, and it can fail as mine did leaking fuel externally. Luckily, if you need to replace, it's not the most expensive part in the world (you need the gasket too). It is a major pain in the butt though if you don't have access to the stbd side of the engine.

captbillc 05-16-2011 10:33 AM

if the diaphragm has a hole in it , the pump should be rebuilt & the oil & filter changed. i have a yanmar2GM20F. i haven't had any problems with it yet. i have rebuilt the pump on a 4 cylinder perkins. i am a retired diesel mechanic, and i have the yanmar shop manual so if you have any questions, i will answer any i can.

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