Community Forums

Gb 63 · 01-01-2021, 05:57 PM

My Generac was doing that and I opened up the control panel and saw that there was a voltage regulator system and when I would jump a hot wire to the fuel pump the light would come on see if there was a wire off your voltage regulator inside the control panel. And also their little green lights two of them they must be on it has to supply electricity to the circuit that runs the electric fuel pump

gmcgene · 01-01-2021, 06:22 PM

I've taken generators to Onan/Cummins three separate times and was charged >$1000 each time. The generator had the same problem after I got it back. In each case, afterwards, I used Flight System's help to diagnose the problem and fix it myself. I'm not a fan.

My Onan experience at Cummins was similar- but not as bad- I only went once.
What was the problem with your generator?

My issue was with the glow plug circuit blowing the fuse. Their proposed solution was to replace the inverter at a cost of $2000, which I declined.

I was able to by pass the glow plug circuit in the start switch wiring. I connected a separate push button switch and fuse to energize the glow plugs. Cost less than $10.00. If glow plugs are needed I just have to depress both switches simultaneously.

I'm sure there is simple, inexpensive way to repair the original circuit, but it's above my pay grade.

I posted this in the hope that someone else has had this problem and can explain how to repair the original circuit it without replacing the inverter.

bilb2765 · 01-03-2021, 02:52 PM

Oil just changed. Check low oil sensor. I had one go bad, and it shut Genny off.

siammike · 01-03-2021, 02:53 PM

Change the fuel pump & fuel filter.

PeterFTH · 01-03-2021, 02:57 PM

I would suspect an air leak in the fuel system - a temperature fault won't shut it down so quickly. Fuel starvation is what I would look for. This may not be a DIY repair - an Onan/Cummins dealer would be the smart place to go as they have the test equipment to trace the problem.

Left2Chance · 01-03-2021, 02:59 PM

Did u try adjusting the throttle?

rbtharris · 01-03-2021, 03:00 PM

Quote:

Originally Posted by dennismhamm

Gen 7500 diesel will fire up and run for about 5 seconds then shuts down. I have changed the temp sensor but did not help at all. If anyone has any info your help will be most appreciated. Thank you in advance.

On a prior motorhome, I had a gas genset. It was doing the same thing. The motor would start and then shut off. Search the forum for "Onan 7500 belt replacement". Spk64 provided a really good writeup for the 7500.

It sounds like you've already replaced the typical maintenance items.

harry2u · 01-03-2021, 03:06 PM

Quote:

Originally Posted by dennismhamm

Gen 7500 diesel will fire up and run for about 5 seconds then shuts down. I have changed the temp sensor but did not help at all. If anyone has any info your help will be most appreciated. Thank you in advance.

On mine I replaced the printed circuit board part was around $450 pled 2 hours labor including diagnostic

Buly · 01-03-2021, 03:07 PM

Diesel engine basically needs only air and fuel to run. If yours starts and runs for 5 min at the time, it means the glow plug etc are fine.
Your problem is in the fuel side. Most diesels also have a very fine fuel filter after the fuel/water separator, usually a spin on.

Marty1096 · 01-03-2021, 03:08 PM

Our generator is connected to how much diesel fuel we have.

Around 1/2 to 1/3 the generator kicks off.

BudMB · 01-03-2021, 03:12 PM

Ours would run for about 5 minutes then sputtered to a stop. Over and over again. Onan changed the fuel pump. It's been running fine ever since.

tom rupe · 01-03-2021, 03:14 PM

Had same problem with Onan 5500 gas. Code said see a dealer which I did. The rubber coupler between the engine crankshaft and the belt pulley was broken so the generator was not turning. No voltage output so computer shut down engine. Good luck.

JPusser · 01-03-2021, 03:23 PM

I had a similar issue on a Newmar gas coach. It smelled like the generator motor was flooded and would only run a few seconds before shutting off. Eventually, it was difficult to even start the generator. Fortunately, we have a local Onan service shop so asked the owner and he said it sounded like the float in the carburetor had a hole and was holding fuel inside. Sure enough, when I removed the carburetor the little white float was full of gas. He gave me a float that he had just laying around in his shop and I replaced it myself. After that it ran fine until the motorhome was sold about a year after the issue arose.

jss540 · 01-03-2021, 03:25 PM

When mine did that I used the generator manual to troubleshoot. Ended up doing some kind of reset by starting it with the switch on the generator housing in the front bay. Kind of like rebooting a computer.