Gen shuts off unless “Start” held down

Is a fault code displayed?

What is the fault code.. When it stops the light will flash (You can also initiate flashing I think by tapping the STOP button) count the nuber of blinks. It will flast 2 or 3 digits then repeat like 2 or 3 times.

If it's 32 than there is another thread on that problem elsewhere.
32 means "Battery low/Not cranking fast enough (officialy) but you know that's not the case since it ran.... Three people I know of had to replace brushes on the generator slip rings.

First off fill it with oil to the full mark

And make sure there is not too much oil in it. I don't fill mine to the full mark any more.

It could be the carburetor fuel shut of valve is stuck in the off condition. Follow the wires to the carburetor and it should lead you to the valve. Disconnect the wires, unscrew the valve. Clean and lubricate it so the rod moves easily. -OR- replace it with a new one.

The other post mentioned needed to have the control board replaced.
You might want to check the connections to the board first.

If an Onan quits running when the start button is released, it means the gen isn't producing power. If it's a newer unit, the starter will kick out and it will run as long as you keep the button pushed so someone can do some diagnostics - like check output voltage. It will not hurt the gen to do this.

your Onan 4KY spec H does not have a low oil level sensor, nor does the control board have fault code diagnostics. OP is probably correct, that generator is not producing AC power, which control board has to "see" to turn on run relay on board. Most common causes are bad field brushes or bad brush contact with rotor slip rings, bad voltage regulator, or bad control board. Worse case scenario is gen. rotor or stator shorted or open winding. Getting to field brushes is somewhat involved, as the fan/flywheel needs to be removed for access. Voltage regulator and control board are expensive items, so throwing replacement parts at it in an attempt to fix it can cost a bunch of $$$ and very possible would not work if brushes/rotor/stator are bad. Replacement control board and voltage regulator are available aftermarket from FLIGHT SYSTEMS in PA. Best bet is to find a qualified ONAN service to accurately diagnose problem. Good luck

Hello all,

I really appreciate everyone’s input and help. (Smile)

Unfortunately, my Onan generator model KY series H does NOT have a diagnostics code light as at least one person has pointed out. You guys ARE able to see the images of my genset, right? (Smile)

Also, they have pointed out that there is NO oil level sensor either. But just to be on the safe side… I will carefully increase the oil level to just below the “FULL” mark with the dipstick screwed in. This one does NOT make sense and I hope it is wrong??

Anyway, I found the COMPLETE FULL original manuals for my Motorhome. They are at least on the level of “Chilton” automotive repair manuals if not as good as “Mitchel” shop manuals; VERY detailed. They were in one of the cabinets and I hope I mentioned that I just bought this Winnebago a couple months ago.

We are having something called an “Atmospheric weather river event” (aka: constant rain) here in the Pacific Northwest and with my health AND my three part time jobs I will continue to diagnose this generator issue as soon as possible.

So next, what I am going to do is:
A: Carefully fill the generator oil level to just below full.
B: Using a long high quality extension cord and my digital VOM (Volt Ohm Meter) I will start the generator and see if there is at least 80 to 90 volts AC (alternating current). This is the minimum voltage that must been seen so it goes into “run” mode. Even better if my VOM shows 115-120 volts AC.

I just wanted to give everyone a heads up and let you all know I am still working on this.

When we get to the bottom of this I will treat everyone out to the beverage of their choice (smile)

(PS. To answer a couple of questions: My genset has 316 hours on it as I mentioned in my OP. (Smile). Also, thank you VERY much for pointing out how corroded the main 12 volt battery cables are at the solenoid…. I DO know the importance of having clean and tight battery cables. I will be splicing in and soldering a good length of brand new cable once I verify that the cost of getting this Gen to work properly is less then say $300. Because I can buy a brand new gas generator (Third party, NOT Cummins) for about $350. And although my battery cables at the Gen solenoid are terrible it cranks just fine.)

Thanks in advance, and I will keep everyone informed.

Hey all,

I wanted to give everyone an update on my generator issue.

I haven’t been able to make any progress on it lately because of work obligations and lack of extra funds but my son in law has a friend that is manager at one of the main trailer and RV dealerships here in Portland Oregon.

I spoke with him the other day and he said he sees this all the time on Motorhomes that sit for a long time. He told me it is a dirty or corroded STATOR…. AND that he has a special tool for cleaning the stator without taking the generator out of the vehicle.

Is this possible on a 2000 Winnebago Minnie with a Cummins Onan Model # 4KYFA26100H generator? Has anyone heard of this? He said if his tool works great. If not, then the stator needs to be replaced which requires pulling the generator.