URGENT: Onan 12.5k Won't Stay Running / fuel pump issue
Hi All - need some help with an Onan 12.5kw Generator - trying to leave for a trip in 3 days but can't keep it running and kind of need it.
First: Rig is 2007 Beaver Marquis on Roadmaster S-Series
Second: Generator is a Kubota powered Onan 12.5 QD
Third: Code the Genset is spitting is 36
Fourth: Fuel is well past 1/2 tank. Added more anyways.
Fifth: Changed air, fuel filters and oil already
Here is the issue, if cold, it will start and run for an hour or so and dies. Won't start again - try priming - no go. Went in for a tune up to see if it was a filter problem. Started, ran for an hour or so and died.
Went back to the truck repair place and we hunted down the issue to fuel pump on the genset losing power after an hour or so. We gave the fuel pump 12v directly and the generator started right up.
Their best guess is a (1) bad fuel pump relay (heating up), but don't know where it is (not on the front/rear run boxes, assuming in the genset somewhere), (2) a bad control board (but can't figure out where it is either - help?) Assuming same as the relay? it is under the black panel on the top front side of the generator but not clear? Or (3) potentially a bad fuel pump that is drawing more current than it should.
I'm hoping that one of you wonderful folks on this forum knows these things better we do - we looked through the Onan Manual and the Beaver schematics and no real solution to a fuel pump relay or circuits (there is a diagram in the Onan book, but it doesn't tell me where the board would be or if there is a removable relay, etc).
Would love any advice on how to get closer to a solution here and what parts I might need to order or hunt down given that I have little time left before we get moving.
Thanks big time in advance. Will keep paying it forward on this forum.
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