Onan 2800 rhythmic surging…how to fix



This is an Onan 2.8 KW generator in a 1994 Roadtrek that hasn’t been run much. Notice when I push on the choke lever part way that the engine smooths out. Push too far and flood engine causing dark exhaust smoke, back off and it runs smooth. Let go and the rhythmic surging returns. How can I fix this?

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10 thoughts on “Onan 2800 rhythmic surging…how to fix

  1. Now this is how I fix mine, I did not want to spend 200 bucks before trying out a couple of cheap fixes, not sure which of the 3 things that I tried worked, but did not spend more than 10 bucks,,,first I bought some of the sea foam spray, and then I took off the air filter and spray, spray really good this stuff anywhere I could get it in, left over night, then I took the plunger valve on the bottom and made sure it was working properly and not stuck, and last I took the black plastic of the altitude adjusting screw, so that I could back off all the way and clean the jet off with some 000 steel wood fine, fine stuff, I kind of buff it,,,and put everything back together and it works fine now,,,NOW you can try one or the other, one at a time and see if it works,,,but I tried everything at once and is working fine now,,,( Microlite 4000)

  2. Carb may be shot…. The replacement is pretty expensive. Try gunk carbreator cleaner…or Onan C9. Spray it in the throat of the carb, let it sit for an hour ….start the generator and spray small amounts in the throat of the carb until it almost stops running… Repeat several times until it runs smooth. It's either going to cost you,$10.00 or $300.00 .

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