Onan 4000 Carburetor problem

[UT-1]

I replaced my Onan 4000 carburetor and now I have trouble keeping it running. It starts okay but dies within a few seconds and I notice fuel spitting out of the front throttle when I took off the air filter. Is there an adjustment I need to tune up the carburetor? I am a newbie and any help would be appreciated. I don't use the generator that much since I have solar panels. Thanks!

[Sappy2]

what was wrong with the original carb?

[16ACE27]

Originally Posted by UT-1

I replaced my Onan 4000 carburetor and now I have trouble keeping it running. It starts okay but dies within a few seconds and I notice fuel spitting out of the front throttle when I took off the air filter. Is there an adjustment I need to tune up the carburetor? I am a newbie and any help would be appreciated. I don't use the generator that much since I have solar panels. Thanks!

Sounds like the new carburetor needs the float adjusted.

[Grumpy Grampa]

If you haven’t already. Pull off the fuel pump line after pump . Check and be sure when you starting the generator the pump is continually supping fuel, not intermittently.

Good luck

[UT-1]

It was gunked up by not running it often enough. I read that some of the new carburerators need to have the air mixture adjusted more than the altitude valve allows - so have to remove the black plastic knob first but it still surges and sputters. Not sure if it is too rich or lean and which way to turn the knob since either way does not seem to make a difference???

[UT-1]

Originally Posted by 16ACE27

Sounds like the new carburetor needs the float adjusted.

how do I adjust the float on the carb please??

[UT-1]

Originally Posted by Grumpy Grampa

If you haven’t already. Pull off the fuel pump line after pump . Check and be sure when you starting the generator the pump is continually supping fuel, not intermittently.

Good luck

I got it running but it still surges and sputters. I had to take off the altitude knob to adjust the fuel mixture more than the knob would allow. It at least will start and run but as above.
Thanks though about the fuel pump - I can hear it run when priming.

[16ACE27]

Originally Posted by UT-1

how do I adjust the float on the carb please??

You have to disassemble the carb - not for the inexperienced.

[MJC62]

Sounds like the float is stuck or as Ace suggested it may be in need of adjustment. If you bought the carb new, then I would call Onan and ask for their help. If it is a float sticking down or a piece of crud between needle & seat then Onan may just have you send it back.

[Skip500]

Mine got gummed up and would not stay running. Took it to an Onan repair shop and they cleaned the carb for $100.00. Runs great since!

[TexAxis]

Originally Posted by Skip500

Mine got gummed up and would not stay running. Took it to an Onan repair shop and they cleaned the carb for $100.00. Runs great since!

Skip, did you take the motorhome to the repair shop or just the carburetor?

[Skip500]

I took the motorhome to the shop and they worked on it with the generator still installed. Took a day. Check with Onan for an authorized repair shop in your area.

[TexAxis]

Thanks for the quick reply.

[pappy18pa]

I had a similar problem and I replaced the fuel pump which is very inexpensive and the fuel filter neither one was that hard to do. It fixed this problem.

[k.maslowski@comcast.net]

Just a bit of advice to anyone having Gen problems. Don't take your Gen to your RV dealer for service. Usually, they do not have small engine people on staff. If you can find a (your brand) generator service center, take it there.

[txc2936@yahoo.com]

OK, here it goes. I put in fuel additive each month. I think this keeps the injectors clean and the ONAN carb clean. Is this an ole wives tale or does this stuff really work? Or does just running the engine and Gen every other week do the same?

For a dollar or two a month i just do this. .....

[Lefty02]

Had the exact same issue after installing a new carb on my onan 4000. The solenoid on the new carb was bad. Took the solenoid from the old carb and swapped it to the new carb. Viola!

[16ACE27]

Originally Posted by txc2936@yahoo.com

OK, here it goes. I put in fuel additive each month. I think this keeps the injectors clean and the ONAN carb clean. Is this an ole wives tale or does this stuff really work? Or does just running the engine and Gen every other week do the same?

For a dollar or two a month i just do this. .....

Different additives do different things. Cleaners do not remove moisture sucked in by the Ethanol which is the bane of modern fuel systems.

[txc2936@yahoo.com]

Thanks, I run the engine and gen pack once every 2 weeks to operating temp. Hopefully, this will heat the system up enough to evaporate water in the manifolds and Gen carb. I also store RV with full tanks, did this on the airplane, supposed to inhibit water formation in the fuel tanks.