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Onan 5.5 HGJAB Spec C generator starts but won't run for more than 4-6 seconds Tim 7-8-15  
Hello. I have an Onan 5.5 HGJAB Spec C with about 450hrs from model year approx 2004. It sat for a few months recently but not terribly long. I just bought the 5th wheel that it came with September 2014 so I've only ran it myself for a few minutes (maybe 10 mins) a few times to make sure it ran, and would operator the A/C etc.

Now I want to use it for real and I have tried many things but it always consistently shuts down within about 6 seconds of starting. The error code is 3-7 which I believe means faulty spark, however I've tried a number of things and none have changed my issue:

- replaced spark plugs and checked spark - all good.
- fresh fuel
- changed oil - haven't had a chance to change the oil filter but can't imagine that would be the issue...?
- cleaned and soaked carb.*
- checked fuel flow and it's strong while priming and while running (for the 6 seconds). I also tried bypassing the fuel power by holding it directly on the positive terminal so it would pump even when the engine wasn't turning over, and it didn't help (i.e. more fuel not needed from what I can tell).
- tried holding down the start button after the engine starts however doesn't make a difference from what I can tell. While doing this I sprayed carb cleaner directly into the carb and it didn't help keep it running either.
- choke seemed a little stiff when I removed the carb so I worked it back and forth a bit, also tried holding it open/closed manually while starting and neither helped (although it did seem to run a little longer into the 6 seconds then when I closed the choke)

* I saw the another post for my same generator below and I'm not positive on the 3 tiny holes behind throttle plate since I'm not sure exactly where that is.

Lastly, I saw the following in a troubleshooting guide and I'm thinking this might be my problem except the oil pressure switch is at least $60 so didn't want to burn that money without being somewhat more sure (if that's possible!). I feel like it has to be something like this though since it fires up and quits so consistently every time - if it is was truly a fuel problem I was thinking it would run rough perhaps or start/stop with some inconsistency - perhaps that's not true either though?

Thanks for any help you can provide.

Q. Why does my generator start and then shut down as soon as the start switch is released?
A. Most models require both oil pressure and AC voltage from the generator to keep running. A lack of AC voltage can be caused by a variety of problems involving the control board, regulator, generator and wiring. A stuck oil pressure switch can also cause this symptom. The interaction between the various components of the system can be confusing during troubleshooting. Use the Troubleshooting Guide to isolate the problem.
Re: Onan 5.5 HGJAB Spec C generator starts but won't run for more than 4-6 seconds John Merritt 7-19-15  
Jumper the oil switch to see if that keeps it running. If it does you found your problem if it doesn't suspect the control board or the fuel pump Also check the fuel line from the carburetor to the fuel tank for any possible leak that will allow air in since this will also shut the unit down.
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