ONAN 4KYFA26100K won't stay running

[Bobbo]

I have an ONAN KY-FA/26100K generator that won't stay running.

I exercise it every month, and this is the first time since 2007 that it won't stay running.

The fuel tank is full.

The oil level is about 1/8 inch below full and WELL above the add mark.

It starts just fine, and the Progressive Industries EMS-HW30C deems the power fine and powers the breaker box. I turn on the A/C or the space heaters, and leave it. When I go back about 20 or 30 minutes later, the generator is not running.

Any ideas where to look?

[Bobbo]

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

[j-d]

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."

[hasheel]

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

[Bobbo]

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

[hasheel]

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?

[Hudsoner]

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.

[Sam_Spade]

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.)

[Bobbo]

Good idea. Thanks for the suggestion.

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.)

[j-d]

Bunch of them on Amazon.

That said, I think I'd put a switch in the wire to the Pump.

Valve's be nice for working on the genset, but how often do you plan to do that?

I think the fuel line is more like 1/4" inside diameter. I had ours off and it looked more line 1/4 than 3/8. Also CD mentioned a 1/4" plug when working on his ONAN.

[Bobbo]

While I am in there, I would like to install a fuel shutoff valve so I can kill the generator by fuel starvation to empty the carburetor. It appears from the documentation that j-d sent me that the fuel line is 3/8" ID and 3/4" OD. Is that correct?

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

Thanks

[Bobbo]

After watching a couple of Youtube videos on changing the fuel filter, I ordered that Airtex fuel pump, a fuel filter, and an air filter. If I am going to go in there, I am replacing all of those parts. I am having them delivered to my daughter's house since I won't be home, but am replacing all 3 while I am in there next month. (I do have a set of TORX drivers.) Thanks for all of your help. I will post a followup after installing them.

[j-d]

This Airtex on Amazon should replace your fuel pump if you decide that's what you want to try. If you search "onan 4ky fuel pump" on Amazon, you'll find several, including this Airtex and a Cummins-Onan branded one at $80-something. One of our OP's has a step-by step for changing it. You need a T-30 TORX Bit in addition to a few ordinary tools.

[Bobbo]

Unfortunately, I am leaving in 2 days for 4 weeks. It will be awhile before I can check anything else out.

The fuel filter has never been changed, so I will get one and install it, while checking for air obstructions.

After it died the first time (while running the A/C), I switched to the space heaters so I would not risk the A/C.

The model number is what Winnebago put in the manual. The actual generator has 4KYFA26100K.

PM sent to j-d

Thanks guys. When I get back, I will let you know what I find.

Bobbo

[j-d]

I think your Model Number is missing a Leading *K* and doesn't have */* in it. Does the Tag on your Genny look like this?



Here's the Owner Manual with Fault Codes. If it blinks *36* which is actually three blinks then six blinks, it probably ran out of gas. We've had a rash of fuel pump failures on these lately. $100 or so part from ONAN, about half that on Amazon.

A few years ago, we lost a few 4KY's with lubrication failure from low oil. By the time ONAN got to Spec *K* the Oil Level Sender had been discontinued. Up to us to keep it full. They're splash lubed like a mower engine, so no Oil Pressure Switch.

I have the Service Manual and Parts List for 4KY Spec K if that's what you actually have. Just PM me with your email id.