ONAN 4KYFA26100K won't stay running

Bobbo wrote:

Anyone know where I can find a gasoline rated shutoff valve that will fit that hose?

First you should be asking someone who knows if shutting off the fuel really WILL empty most of the fuel from the carb or not.
Some leave the bowl half full and that isn't hardly worth the trouble.
(Small engines in general, that is.)

Mine started to do the same, died after a while running really well, sometimes up to two hours. After having replaced everything (oil, plugs, wires, fuel filter, etc.) my son (Ford Master Mechanic), and I came to the conclusion that the unit stops running because of fuel starvation (probably vapor lock because of the poor cooling inside the generator compartment). We plan to install a push pump in line with the fuel pump of the generator to overcome this problem.

Kind of long reply, sorry. Mine was doing the same thing. I replaced the fuel pump and filter. No gas was coming out of the fuel line when I cranked it.
After changing and reassembling. I have no 12 volt power at all! It gets better. Before I wrote this post, I cranked up the engine on the motorhome. The 12 volt system came to life. I tried to start the generator. I heard a click, and no 12 volt power. Restarted the engine, 12 volt system came back. Got the generator started.I heard a click again, no 12 volt power.
What did I do wrong?

Sounds like a breaker tripping. Do you have a short circuit?

I have checked every fuse twice. It's a head scratcher

Bobbo wrote:

I have ordered this push button switch. It is a marine switch so being exposed to the elements should not matter. I can put connectors on the wires matching the ones on the Airtex pump and it will be plug-n-play. (Also easy to remove if problematic.)

I'm wishing the switch wasn't push button. Gonna have to be sure you or somebody else didn't push it to OFF or leave it in OFF and here you are wanting to use the generator. If you mount the switch near the generator, you can do the first priming of a trip at the generator, and be sure you hear the pump. Just impose a stiff penalty on anybody going around pushing buttons.

The valve idea inspired me. I ordered that guy and will install it next time I have the fuel line off. But just-in-case I need to work on something.

Those concerned that "running it out of gas" will leave residual in the carb have valid concerns. That's why I don't suggest that. Personally, I put stabilizer in every drop of gas I buy, and also exercise the genny.

Carbs have brass jets and other brass parts. Brass is part copper, and copper promotes formation of gum with gasoline. So it's indeed possible the thing could run out of gas but leave some gas in contact with a brass jet and end up gumming it. Reduced chance, I'll admit. The gas could easily evaporate first.

I do the stabilizer/exercise thing because I've had to replace a carb and I no longer "Feel Lucky."

OP here. Finally back with the solution.

I decided it was a faulty fuel pump. I bought a new fuel pump, fuel filter and air filter. I also bought an ON/OFF switch so I can kill the generator by turning off the fuel pump.

I opened it up. Got all of the stuff out of the way so I could get to the fuel pump. I had ONE SCREW to remove and the job would be over. I COULD NOT get that screw loose. I sprayed it with penetrating lubricant for 3 days. I used a ratchet for torque, and even hit the handle with a hammer for shock. I bought an impact driver. No luck.

Finally, I gave up and put it all back together. I took it to Cummins/ONAN. It took them 3 days to get it back to me. The paperwork that I got when picking it up said that the screw holding the fuel pump in was rusted in and had to be cut out. They drilled out the hole and put in a nut and bolt to hold the new one.

They would not use the hardware I had bought, so I have spares, and no ON/OFF switch still.

Sigh.

Bobbo