Class C Onan Generator Exhaust Stack Issue

[Moonalisa99]

We have a 2004 Class C with Onan Micro quiet 4000 generator. The generator only has 188 hours on it. Surging problem, tried Seafoam fuel cleaner first. Seemed to help, but when putting a load on generator would intermittently surge. So we replaced the carburetor (does seem to be running rich) & fuel filter, surging gone. Tested out several different times before going on trip. Would turn on A/C, ran perfect for extended periods, smooth, no surging. When we attached exhaust stack (cannot remember brand, but purchased from Camping World) at tailgating site, problems with generator dying was intermittent. Would run fine. Turned generator off for a period, would try to restart & problems. Noticed after we removed exhaust stack the generator would start right up, run fine. Any suggestions?

[hohenwald48]

Can you read the trouble code?

https://thecampingadvisor.com/onan-generator-fault-codes/

[Moonalisa99]

Thanks! I mistakenly said we replaced carburetor & it was the fuel pump & fuel filter. After replacing those the generator ran like a kitten. We went tailgating for 2 days & nights & generator would run for up to 3 hours. The problem was intermittent. We got home, I ran the generator for 2 hours while cleaning & reading for next trip, no issue, so I don’t think it is the new fuel pump or filter. The only thing different than when we ran it after replacement of pump & filter, was the stack & the oil showed a little low, we had topped it off. We have been advised to remove a pint of oil, dipstick level should be just above low mark. When oil heats up, expands & too much oil may be the issue. If it dies & restarts after 30 mins or so, gives oil time to cool back down. Makes sense. Will post if this helps.

[garyemunson]

A Genturi type stack is not going to cause the generator to "die". An Onan that intermittently shuts down then restarts OK after a while is almost ALWAYS a failing fuel pump. A known issue on these generators for many years. $20 on Amazon.

[IB853347201]

enblethen wrote:
Too much back pressure with the add-on exhaust stack

X2
And I believe I read somewhere that Onan does not recommend their use.
I used one once and had similar issues. Got rid if it quick. No more issues.

[enblethen]

Too much back pressure with the add-on exhaust stack

[Moonalisa99]

Could you expand on your comment? Is this from experience???

[IB853347201]

Suggestions? Only one. Return the exhaust stack to Camping World for a full refund.