Onan 5500 surges and stops in hot weather

[abarkl]

My 2001 Onan 5500 gas generator surges and stops after about 10 minutes when the outside temperature is above 90F. It's done this for about 2 of the 5 years that I've owned it.
I've replaced the oil, filters (gas (2) and air), and plugs as regular maintenance.
Of course I live where it's hot (Phoenix) and can't use the generator except in the winter time or once I've traveled 2 hours or more north in the summer time.

Any thoughts or ideas?

["007"]

Your manual trouble section has fault codes that may help you. Insert HGJAB SPEC-D
Your altitude adjustment for carburetor maybe causing a problem.

[Sammie]

It sounds to me like your fuel supply line may be bad or cracked and damaged. Also could be a bad fuel pump. In hot weather you might be experiancing fuel starvation or vapor lock. Check the fuel filter if there is one.

Sammie

[hamguy]

Quote:

Originally Posted by Sammie It sounds to me like your fuel supply line may be bad or cracked and damaged. Also could be a bad fuel pump. In hot weather you might be experiancing fuel starvation or vapor lock. Check the fuel filter if there is one. Sammie

What you said.

[Ray,IN]

X3! I've had flexable gas lines fail inside but look new outside. That was on a 2005. This gas line is cheap to replace.

[Clay L]

I had a similar problem that I thought at first was related to heat but wasn't.
It turned out to be a loose fuel line hose clamp at the transition from rubber to metal near the tank that allowed air to intermittently enter the line.

[blacktie.shooter]

Quote:

Originally Posted by abarkl Of course I live where it's hot (Phoenix) and can't use the generator except in the winter time or once I've traveled 2 hours or more north in the summer time. . .

I believe I'm missing something . . why can't you use your generator in the summertime? Seems to me, that's when you really need it, down where you live.

We left there in early May, the temps weren't in the teens yet, but we sure as heck ran the generator and both a/c units on the way back north, and had no problems. If you can't use it in the hottest part of the summer, why have it? (That sounds s/a, don't mean it that way, just wondering what it is you know that need to find out about.)

[abarkl]

Today it started and ran for 5 minutes with a 110F ambient temperature but shutdown hard. My volt meter was wavering between 112 and 118 but that's when it first started and it probably would have settled down.
I removed the access panel to check for codes but I didn't see any. There was plenty of oil colored smoke. I think it probably has a bad head gasket or oil seal. I will start and run it again later this week when I'm up north.

[bjsheldon]

Quote:

Originally Posted by abarkl My 2001 Onan 5500 gas generator surges and stops after about 10 minutes when the outside temperature is above 90F. It's done this for about 2 of the 5 years that I've owned it. I've replaced the oil, filters (gas (2) and air), and plugs as regular maintenance. Of course I live where it's hot (Phoenix) and can't use the generator except in the winter time or once I've traveled 2 hours or more north in the summer time. Any thoughts or ideas?

I had a similar problem and it turned out to be a faulty fuel pump. Seems Onan used a second sourse for fuel pumps and the have a seal in it that swells with temperature and the fuel pump quits working. Most service people and Onan distributers don't know of this problem. I ended up getting 3 pumps and numerous phone calls to the Onan factory before they told me of the problem and sent me a good pump. One way to check is to run the generator off an external tank with the hose connected to the inlet of the fuel filter. The external tank must be higher than the carb for the siphon effect to work.