Cummins Onan 5500 Generator

1Wheeldrive wrote:
If you can smell fuel after priming it, then the fuel pump is probably working, and it may be flooded. You should look at the spark plug to see if it is wet, or showing a rich condition.
I am another person who has never had a problem with my Onan 5500 Marquis Gold genny, have had it for 3 seasons, use Stabil, exercise it once a month in the off season for 45 minutes to an hour at 1/2 load. Try to fill with fresh gas at or near the end of the camping season. I have about 105 hours on the genny.

I had mine for over seven years with almost 440 hrs on the Onan with no issues. Ours was run at least once a month and the fuel was constantly cycled through the tank since the fuel station was also fed from the same 40 gal tank.

Old fuel could definitely cause your problems...