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bjhamlyn's avatar
bjhamlyn
Explorer
Dec 17, 2014

Onan 4KY F series Gen Only runs while I hold the choke open

I know there are a million Onan posts out there, but I haven't found quite what I am looking for yet, so I figured i'd ask here.

I have an Onan 4KY F series generator with a little over 200 hours on it. The generator is in a motorhome that is new to me. The generator had not been started in several years. I checked it our, put in new batteries and checked the oil level then tried to start it. It started for a few seconds when I used starter fluid, but then shut off. I decided that I needed to remove the carb and clean it. I used a 1 gallon can of carb cleaner from advanced auto parts (the kind that you lover the parts into), and disassembled the card as far as possible then let it soak for about a half a day. I then drained the solvent out if it and cleaned it watch spray carb cleaner, then dried it with my compressor. Now the generator starts up, but will only keep running if I hold the choke all the way back (wide open). I have tried adjusting the main adjustment screw (altitude screw). I even removed the plastic limiter to adjust it several turns in each direction. Nothing seemed to help. I tried to remove the air cleaner to see if maybe it was restricting air flow. I noticed a slight difference, but it would still shut off as soon as I released the choke.
What is the problem? I just read something about the generator not running if the motorhome fuel level is below 1/4th of a tank. I think mine is right about 1/4th now. Could that be the problem? Is my carb probably still a little gummed up? Is it an electrical problem? Maybe the oil level switch went bad?
Thanks,
-Brandon
  • Great news! The second cleaning did the trick. I guess I just didn't soak it long enough. I soaked it this time for about 1 1/2 days, then cleaned it with carb spray, to include all of the little holes. I then blew it off with compressed air, to include all the little holes again. I put it back on the generator and it started right up. Then it shut down after a few minutes. Turns out I had to adjust the "altitude" screw. I tightened it up until the engine was about to stall, then backed it off a little until it was running pretty good. Then I put a load on it and let it run for about 40 minutes just to make sure everything was good. It was, and I left a happy man.
    Thanks for all of the help everyone. Couldn't have fixed it without you all.

    -Brandon

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