Onan Marquis 5000 quits after a while?

[nehuge]

I have a BGM series Onan Marquis 5000 which fires right up. After about 20 minutes it just randomly dies. Then it won't start for 10 minutes or so then will fire up again. Sounds weird, but it seems to do this when it is the generator by itself. With the motorhome's engine running it doesn't seem to do it. Any ideas? It is 1/2 tank full.

[nehuge]

I think it's better now. It was almost 'rattling' or knocking kinda like it does when you turn it off (just as you turn it off and it sputters, it does kind of a knock as it dies). It was doing that like it was at too low of a rpm. The owner told me that the generator was serviced last year. I have done a new fuel filter before I posted this problem. Today I found the air filter to be dirty, as well as a little foam piece wrapped around the fuel filter.

Even though I put fuel cleaner through the tank, while I had the air filter off I ran carb cleaner through the butterfly on the carb.

It seems to run better and hasn't stalled.

What's weird is that the air filter seemed to make a difference, and even to test that I covered the entire air intake with my hand and it wouldn't die. What the hell? lol

[nehuge]

I'll put it on summer and then raise the altitude up a tad. Will also check voltage and report back.

[clydedoerr]

This may sound crazy, but it doesnt cost anything and only takes a couple of minutes. My Onan 4000 Gen did the same thing. There is a lever on the carburetor, mine says altitude, but whatever it says, raise if up some. Took care of my problem and now it will run 48 hours without shutting down. Would shut down every 20 mins before I did this. Makes no sense but it worked for me. Good Luck

[Jim]

What's the AC voltage when it's running? If it's close to too high or close to too low, that'll shut it down. As the generator heats up, the voltage will rise a bit. Under normal circumstances the voltage regulator will keep it below 128V so monitor it while it's running.

[Yankee_Clipper]

One other thing to check is the switch on the carburator that has a winter/summer selection. The winter setting preheats the intake air, and could cause vapor lock in warm weather. During the late spring/summer it needs to be on the summer setting. HTH.

[jtovosr]

Don't know if your generator is diesel but my Onan 5000 would run for 15-20 minutes & cut off, turned out the water pump belt was broke & when the computer sensed the generator water not circulating it shut down.

[nehuge]

Rig is a 1995. Even when the engine's running the generator seems to run too? I turn off the engine, and 10 minutes later the generator dies. This only started like 2 weeks ago.

[crasster]

I'd check the fuel filter/pump.

[John_Wayne]

How old is the rig it could be that it is developing cracks in the rubber fuel line to the generator from the main gas tank. If so you will have to drop the tank to repair. A way to find out Take a gallon of gas in a separate gas can run a hose from the gas can to the generator fuel pump bypassing the rigs gas tank if it runs for more then the 20 min. you have found your problem.

[tatapepek]

had same issues -check fuel pump