2019 Onan 4000 KY RV gas generator issues

[Db327]

Thanks everyone for your research and suggestions!

It's definitely getting fuel. I can hear it, and the fuel bowl fills up.

When all this started, the oil level was at the bottom of the dip stick. I added a little oil to bring the level to mid-stick.

I don't think it's an electrical issue. The gen consistently works ok for 1-2 minutes when cold. And, I can force it to run for a few more minutes by holding the throttle open. It won't start at all when hot, and something, maybe the governor, physically stops me from holding the throttle open.

It sounds like the best bet is to try an OEM carb. If it still fails with a brand new OEM carb, maybe I can then try to get the remaining problems fixed under warranty. I don't want to spend too many hundreds blindly changing parts, but I also don't want a $2500 repair bill.


Thanks again!

[Knoll52]

Had the same problem with new onan gas generator. 3rd Cummins dealer discovered the problem with the starter board after it was removed and torn apart

[randomledder]

Are you sure you have the choke linkage arm on the carburetor the correct way around. I have seen it more than once where when hooking up the choke linkage the arm gets turned around to the other side of the carburetor and as it warms up it actually closes the choke more. Typically they start cold and run for a couple minutes before flooding out. Just a thought.

[Db327]

Good suggestion, thanks. My before and after linkage pictures match

[Db327]

I got the OEM carb today and installed it. The generator runs like new.

I'm relieved, but disgusted by this design and by the need to run it every month. My 20 year old (Briggs engine) lawn tractor doesn't need such pampering.

[OldWEB]

Originally Posted by Db327

I got the OEM carb today and installed it. The generator runs like new.

I'm relieved, but disgusted by this design and by the need to run it every month. My 20 year old (Briggs engine) lawn tractor doesn't need such pampering.

Good on you!

[SBG]

I also had a 1 year old generator that would not start. I drained the float bowl, then disconnected the fuel line going to the carb. Using a small funnel i filled the carb with 100% fuel system cleaner and then cranked the generator for 30 seconds. After 30 minutes I drained the bowl reconnected the fuel line and it started up.

Since then I added a fuel cutoff valve before the carb. I now run the generator dry if I am not going to use it in a short period of time. It now starts better and run smother.

Steven

[NackDSP]

Originally Posted by SBG

Since then I added a fuel cutoff valve before the carb. I now run the generator dry if I am not going to use it in a short period of time. It now starts better and run smother.

Steven

I've used the "run it dry" method on my pressure washer and home backup generator and that has worked perfectly for more than 15 years now. I think I will do the same. Shutting it down with the inside kill switch is likely just killing the spark so there is unburnt fuel left in the cylinder/s just washing the oil away from the rings on each shut down. Running it dry would avoid that.

Any photo or parts used for of the cut off valve install would be great.

[twinboat]

Originally Posted by NackDSP

I've used the "run it dry" method on my pressure washer and home backup generator and that has worked perfectly for more than 15 years now. I think I will do the same. Shutting it down with the inside kill switch is likely just killing the spark so there is unburnt fuel left in the cylinder/s just washing the oil away from the rings on each shut down. Running it dry would avoid that.

Any photo or parts used for of the cut off valve install would be great.

Now days, the generators have a solenoid on the carb main jet that closes when you shut it down.
Its call fuel cut off valve and it prevents gas from drawing in as the engine spins down.

No gas wash or run on, from hot spots.

[1982]

If you last ran it with fresh Top Tier gas in it, is it worth it to drain the bowl if you will not run it for 4-6 weeks?

[twinboat]

Originally Posted by 1982

If you last ran it with fresh Top Tier gas in it, is it worth it to drain the bowl if you will not run it for 4-6 weeks?

Yup, even good gas has ethanol in it and can seperate over time.

Then the gas evaporates, leaving behind the ethanol. Ethanol absorbs moisture and moisture causes corrosion.

Someday, generators will have fuel injection and all of these problems will go away.

[Isaac-1]

I feel 6 weeks is pushing it on letting a generator sit without running. I unintentionally let mine sit for 7 weeks earlier this year with Covid going on, and even though I put a new carburetor on it last year, it would barely start after multiple cranking attempts where normally it starts on the first or maybe second try. Speaking of which it has been about 3 weeks since I started mine, I guess I better do it.

[URTHllc]

The problem is these Carbs are so small and the ports and such are so small that the tarnish completely stops them up and it is impossible to clean out or dissolve. Same as on Weed eaters, chainsaws, etc...

[THenne1713]

1) (Since you have new carb) After a run/die or start attempt, pull the BOWL DRAIN SCREW and see if carb is getting fuel? Suspicion is you have a FUEL PUMP issue, (which is common, esp. if unit is not run regularly), but also possibly fuel gum or ethanol debris related (white residue or stones in the check valve/s: CHECK OM for picture of carb/ screw if not familiar w/ drain? If carb dry, double check FPUMP FUSE and verify power to pump during run? These pumps are magnetically sliding piston, w/ check valves and no rotating parts; 2) Make sure RIG is level and bring OIL Level to FULL mark; 3) Throttles open w/ SPRING pressure, but GOVERNORS CLOSE throttle w/ solid rod connections, opposing that spring pressure.