ugh we just got all of our problems fixed in our onan and it sounds like we have the same probs so heres what i did
1. fuel filters
2.fuel pump
3.spark plug
4. check fuel lines (ours had a pin hole that caused alot of problems)
5. we had to buy a new carb (main problem)
we took it to a shop for the new carb and they said onans carbs are really tuchy and should be started atleast once a month
hoped this helped