Generator help please

[revrick3]

We have a 2003 Newmar Mountain Air with a Generac Primepac 66G generator. Only has about 600 hours on it and I put most of these on over the past 3 years. Having some trouble with it and am asking for some help. Just serviced it, new air, oil filters and oil. New plugs. Had new exhaust put on on West coast trip last summer and choke cleaned and adjusted. We ran it every day for a 3 week trip back from California last fall and due to health issues we haven't traveled far until this summer. I have ran it with a load several times over winter. Started on trip couple months ago and it started acting up.
Now it starts fine and runs under load for about 15 to 30 minutes then shuts off. It will restart fine but then stops again.
Oil is good, Thought at first it was low fuel as only had 1/4 tank, filled up but still same. Changed fuel filter few months ago. I put Sea Foam in every few months. Thought it was overheating so opened door but still stops. Going down road it acts exactly the same. Not sure if its fuel pump, temp switch or oil switch. Or some other issues I haven't thought of. Any ideas guys would help. When its running it powers everything fine but cant get more then 20 minutes until is stops.

[BCarp]

The high temperature cutoff switch is located just above the oil filter. According to the manual, it's a normally open switch. Right after the engine shuts down, check for continuity on this switch. If you get continuity, that's why the engine shut down. The switch is supposed to close at 270 F, if the engine is not that not and the switch closes, you need a new switch.

[revrick3]

Originally Posted by BCarp

The high temperature cutoff switch is located just above the oil filter. According to the manual, it's a normally open switch. Right after the engine shuts down, check for continuity on this switch. If you get continuity, that's why the engine shut down. The switch is supposed to close at 270 F, if the engine is not that not and the switch closes, you need a new switch.

Any other ideas from the great minds here. Is this possibly a fuel issue.

[twinboat]

Some reported a fuel evap, charcoal filter issue that caused a vacuum in the gas tank.

As a test, try running it with the gas cap loose enough to act as a vent.

[monte433]

Originally Posted by twinboat

Some reported a fuel evap, charcoal filter issue that caused a vacuum in the gas tank.

As a test, try running it with the gas cap loose enough to act as a vent.

This is going to sound stupid but when I was researching troubles with my generator, I ran across a post that just said take a pint of oil out of it, after I exhausted every other possibility, I removed a pint of oil and it worked, don't know why or how but it did. I have and Onan 5000 not sure if this will work for you.

[twinboat]

Originally Posted by monte433

This is going to sound stupid but when I was researching troubles with my generator, I ran across a post that just said take a pint of oil out of it, after I exhausted every other possibility, I removed a pint of oil and it worked, don't know why or how but it did. I have and Onan 5000 not sure if this will work for you.

Removing oil from an Overfilled engine stops the sump oil from reaching the rotating parts and foaming up.

Foamed oil can cause a drop in oil pressure, fool the oil level sensor and shut down the engine.

[monte433]

Mine wasn't over full

[revrick3]

I check oil regularly as when its running long it does use a small amount and I have to top it off with about 1/4 cup after 24 hours. But its at correct level now. I did learn that one myself last year when I had it slightly overfilled once.
Is it possible a bad fuel pump is the culprit.

[96 Wideglide]

I would try running it from a portable fuel tank. Yours is about the age the fuel line may be deteriating and allowing air in.

[revrick3]

Seems it was high temp switch bad. Went to take wire off and switch broke apart. Ordered part and replaced it. Ran over hour 2 days in row. Laser temp shows about 230 at oil switch. Thanks guys for help. Ordered fuel pump and will hold on to it until needed