I have a Class A gasser with the 5500 Onan generator. It has only 70 hours on it and it has run just fine until recently. I start the generator from the inside control panel and it has no problem starting and running perfectly even under A/C load. Anywhere from 15 to 20 minutes the generator starts to stall and seconds later, it quits and cannot be started I let it sit for an hour and I can start it up again..... 15 minutes, same stalling occurs.Any thoughts on trouble shooting?Thanks,Racorman

Does it have a low oil automatic shutoff?

Mine is doing the same thing. I suspected the fuel pump. When the gen quit, I opened the carb drain and pressed the prime button. No fuel. Later when the gen would start, i shut it down before it quit on its own. I repeated the above and fuel came through.So, I have a new fuel pump, fuel filter on order.I anticipate that this will fix it. If not, on to the next possibility, which may require expert help.A friend of mine had the exact same problem, and this solution solved his problem.Good luck! Is your under warrantee?

I had the same problem with mine when brand new and the dealer could not fix it. I lost patience with them. On mine the fix that worked was to lower the altitude adjustment. Evidently it heats up and narrows a passage. I had bought a new fuel pump and fuel filter. They are now spares.

Onan 5500 Stops Running after 15 minutes | Good Sam Community

pfidahospud
Explorer
Jun 05, 2017
Does it have a low oil automatic shutoff?
rk911
Explorer
Jun 05, 2017
any error code on the panel?
Ltrip
Explorer
Jun 05, 2017
Mine is doing the same thing. I suspected the fuel pump. When the gen quit, I opened the carb drain and pressed the prime button. No fuel. Later when the gen would start, i shut it down before it quit on its own. I repeated the above and fuel came through.
So, I have a new fuel pump, fuel filter on order.
I anticipate that this will fix it. If not, on to the next possibility, which may require expert help.
A friend of mine had the exact same problem, and this solution solved his problem.
Good luck! Is your under warrantee?
Crazy_Ray
Explorer
Jun 05, 2017
Need fuel pump
Heisenberg
Explorer
Jun 05, 2017
I had the same problem with mine when brand new and the dealer could not fix it. I lost patience with them. On mine the fix that worked was to lower the altitude adjustment. Evidently it heats up and narrows a passage.

I had bought a new fuel pump and fuel filter. They are now spares.
Ltrip
Explorer
Jun 05, 2017
Heisenberg, Can you be more specific on your altitude adjustment?
I live in Reno, Nevada, at 4500' elevation and usually go up or down from there. So I check this often.
If you are actually at 3000', for example. Do you set the gen to be 2000'? Or what?
I know it is difficult to be very accurate with the adjuster.
Thanks!
Heisenberg
Explorer
Jun 05, 2017
Mine was set for our elevation roughly 3200 feet. I went lower to about 1500 ft and my problem went away. I am sure it is a mechanical adjustment and it seats after heating up cutting the fuel off. Mine would run 30 to 45 minutes before sputtering and eventually dying.
Racorman
Explorer
Jun 05, 2017
rk911 wrote:
any error code on the panel?

All it shows is off and on :R
Racorman
Explorer
Jun 21, 2017
I took the motorhome to a Onan dealer and he suspected the fuel pump and recommend I replace it. He wanted $172 for it and a filter just for the parts.

I went ahead and found out that Airtex makes the fuel pumps for Onan and I ordered one on Amazon. Airtex E11015 Electric Fuel Pump for Onan Generator Set for $44

Here was one of the comments on Amazon:
This was an exact replacement for the original Onan/Cummins 149-2620 fuel pump. My original fuel pump developed the fairly common problem of causing the generator to stall after about 20 to 30 minutes then requiring a cool down before it would restart and run for another 20 to 30 minutes. I only have about 15 hours on the generator since replacing the pump, but so far, so good.
etrippe
Explorer
Jun 22, 2017
I have the same problem and at this point I'm pretty sure it's the fuel pump. Onan gave me the part number and I searched amazon and saw the Airtex pump at half the price. But before I order the Airtex, I wanted to ask the question on this forum. Thanks so much for posting. Any installation issues?

thanks in advance

eric