Onan 4000 not wanting to stay running

I'm not a tech, but based on my experience with carb and surging problems on two 4KW ONAN genny's (a 4KY like you have and an older BFA):

In both cases the carburetor required repair/rebuild/replacement.

I also think:

Governor adjustment is a possibility but a thin chance. I'm trying to resist saying I think you're kidding yourself...

You need a higher concentration of Seafoam or other carb cleaner than you can achieve in your main tank. Those of us doing that treatment hook up a small tank with a very high concentration in it and run the genny on that.

I've also heard of taking the fuel line to the carb off, filling it with straight Seafoam. Start the genny, let it idle a few seconds, shut it off for half an hour. Repeat, Repeat, Repeat... The idea is to work the Seafoam into the genny carb's VERY small passages and let it soak there.

Spraying a cleaner into the carb throat does very little. You need to clean where the gas is dispensed INTO the carb throat. All those tiny passages...

SeaFoam is definitely cheaper than a new carb. Definitely will try that right. I've also read about people pushing Seafoam directly into the intake of the genset as well.

Only downside -- if you SeaFoam the generator by putting it in the fuel tank, you will be SeaFoaming your engine as well, so I'd probably consider an oil change after you run that stuff through the lines.

Thanks to all of you.

I'm going to start with the governor adjustment and go from there. This RV sat idle for over a year, but I have had it to Ft. Worth for the NASCAR races twice and ran the generator for both trips. It's possible that I just need to run it more because before this weekend that last time it was run was about two months ago.

If I decide to run some seafoam through it I will just add it to my gas tank, right. I will also track down the fuel filter on it because I do have the manual for it.

I will keep you all posted on what it turns out to be.

Jerry

Jerry_Amerson wrote:
Hey you all,here I am again.
I have the Onan 4000 generator and it wants to die on me when I get it going and roams up and down before dying. If I wedge something in by the governor to keep it from roaming it will run fine. Is there an adjustment I can make or do I need to replace the carborator on it.

Thanks again for all your help!!
Jake

I will say again if it runs fine with something wedged in the governor it's not a problem with the fuel, fuel filter, or carburetor. While I've had other generators the Onan is new to me so I like to read up on issues like these so I can be prepared should something like this happen to me. Apparently on these generators there's an adjustment at the governor arm pivot point. In my humble opinion you should start with that. There's a decent utube video on this at https://www.youtube.com/watch?v=KlhYg0iXbSA. Also keep in mind that the generator hunting like that can cause damage to things like microwaves and TV's. Whatever the problem hope to hear how you corrected it.

Replace the fuel filter for sure.

I agree about the governor. If you get it revved up, does it run smooth? Are you starting it with a load? Be sure the shore power cable is NOT plugged in, so that you can confirm the generator surges no matter what.

Mine was surging like crazy when I bought my RV. I adjusted the governor by plugging in a kill-a watt meter and confirmed the revs were set correctly by watching output voltage. Find a manual to confirm, but believe the right number is 125 volts with no load.

Jose

Before I spend money on sea foam or anything else... you say if you wedge something in by the governor it runs fine. while I'm not sure what to look for this would indicate to me there's nothing wrong with the fuel supply and you need to look elsewhere.

Seafoam and change the fuel filter.

Always do the simple, easy things first.

Putting cleaner like seafoam through the carb is a good idea.

It may also be not getting a good fuel supply—either the level in the tank is nearly too low, or there's a slight leak in the line to the generator letting air in, or maybe even the line has bubbles from sitting unused for a long time and the gas draining out. Mine will hunt for a minute or so when first started after sitting for a few weeks because of this, but then settles down and operates perfectly.

What they said. But it also sounds like it needs to be run.

F1bNorm wrote:
Step one for me, would be to run a can of Sea Foam through it.

And if he did not I would