Generator Stops Running

Frederick · 08-17-2020, 06:27 PM

Hi everyone,

I had a friend stop by that is having generator problems. The generator is an Onan Cummins QG RV 4000. When he arrived the generator would not start without starting fluid and then would run for anywhere between 15 minutes to 30 minutes and then die. It sounded like fuel problems and a gunned up carburetor so I disconnected the fuel line and ran an independent fuel line and bottle with Chevtech fuel cleaner which helped a little, but it eventually went back to stopping after about 15 minutes. So I took the carburetor off and disassembled it and cleaned it and afterwards it ran great for about 1-1/5 hours. When it died it definitely stumbled like it had plugged ports so I removed the carburetor again to find pieces of varnish in the fuel bowl. I cleaned the carburetor again and reinstalled. This time I put an inline fuel filter between the fuel pump and carburetor so if the pump was kicking out some dislodged varnish the filter would catch it before it got to the carburetor. The generator ran for a little over 4 hours of under full load with the air conditioner running in 92 degree weather then stopped. 4 hours is a good run so I don’t think it fuel anymore.

Are there any circumstances where in 90+ degree weather a generator will shut off if it gets to hot?

Any suggestions welcome. Thanks in advance.

Winterbagoal · 08-17-2020, 07:21 PM

Is the oil level good, they have a low oil shutoff?
I seem to recall that some of the Onans have a high air intake temperature sensor that might be flakey. It's usually located inside the air intake (go figure) and there's a few threads out there about pulling it out of the intake, and letting it dangle outside by the wire it's attached to, and the generator would run fine. IIRC it was for a QD3200 diesel generator, so it might not apply to your situation.

Morich · 08-17-2020, 08:07 PM

I might be looking more at the fuel filter being clogged again!
Part of that comes from the genset is not all that big and 90 is not all that hot as we here in Texas are hoping to cool off and get down into the 90's for a few days......

But write that down as pure BS guessing and thinking simple!