generator issue

[golfoh1]

gas generator onan 5000? anyway it starts and runs for about 45 minutes then it stops. If i wait till it cool down it goes againg runs awile then stops. any ideas.

[wildmanbaker]

First CHECK the oil. If it does not dribble out the fill hole, add until it does. If it is in any condition at all, it will pump a lot of oil into the engine, and it will shut-down on low oil level. If this does not fix it, follow Michael's recommendations for testing.

[hohenwald48]

Seems like every time this topic comes up it ends up being the fuel pump.

[mfox20]

You didn't say how old your 5000 was but I have had the same experience on my 2000 Onan 5500. Problem showed up in summer heat, would run great on the road for an hour or two and shut down. Cool off an hour or so and it would run again. Certainly appeared to some sort of fuel pump issue in the heat.

Turns out it was the fuel line leaking air coming from the main tank.
It is an easy check to disconnect the fuel line at the pump and replace with a short hose dropped in a gas can. Mine ran in the driveway for 6 hours in 100 degree heat and never shut down.

I replaced all rubber hose and metal hose sections with a new one piece heavy duty fuel hose and my problem was fixed. No issues 4 years later.

Cheap test and fix. Certainly can test the fuel pump as well, and that could be it, but if its the fuel line a new pump won't help.

[darsben1]

Quite a few threads on fuel pump overheat in the past. Some chose to move the pump off of the Genny onto a sidewall to permanently cure the problem

[harley-dave]

jy wrote:
when mine did that it turned out to be the fuel pump getting hot and quiting.Confirmed this by having a fan blowing right on the fuel pump and the gen set ran for hours.

Ours did exactly this and it was the fuel pump. It would get hot and stop working. Had to sit for a while before it would start.

Dave

[Matt_Colie]

Golfoh,

Now you have some guesses, and that is all anybody can do from internet land...

So, put aside the time to run it and do a diagnostic. The first and simplest should be to pull a plug wire and put a screw driver in the cap and hold it near (1/8~1/4") something and crank.
Do you see/hear a spark??
Yes, then it is a fuel problem and probably the pump.
Put the wire back on and squirt some fuel into the carburetor.
Does it fire now? Fuel problem confirmed.
No, then you have an ignition problem.

There things are neolithic (new stone age) technology, so get out the Onan book and track it down.

Mine are both 45yo and have bouquo hours and the one in the coach will start and run as long as I keep it supplied with fuel. The other one does not have a battery because I stole it to start the snowblower.

Matt

[jy]

when mine did that it turned out to be the fuel pump getting hot and quiting.Confirmed this by having a fan blowing right on the fuel pump and the gen set ran for hours.

[rrupert]

Dirty and/or gummed up carburetor.

[ford_truck_guy]

low oil level?

[wra]

There were other threads with the same problem. The suggestion was that the gas cap may not be venting. Try taking the gas cap off to see if that is your problem. If so buy a new gas cap.