1. Onan Engine Carburetor Parts

This is the service manual for the KV, KVC, KVD se. When contacting Onan for parts or product informa- tion, be. Stickingchoke or carburetor mixture. Onan MicroLite 4000 Series Service Manual. Onan rv genset service manual (86 pages) Portable Generator Onan EGSAA Service Manual. Onan egh, egs portable gensets service manual (119 pages). Carburetor Replacement (Beginning Spec D) Other than turning the altitude adjust knob shown in Figure 8-10 (which changes the main fuel. Parts Manual Commercial Mobile Generator Set HGJAD (Spec A−E,J) HGJAE (Spec A−E,J-K). Service and repair of Cummins/Onan equipment must be performed by trained, experienced personnel. Gasoline Carburetor, 12, 13 Gasket, Gasoline Intake Manifold, 12, 13.

I have a 4.0BFA1R Spec letter C Rv genset. It had been sitting for a while and the carb had some water and sludge in it. I have cleaned it twice and everything looks good.

The engine runs great but surges at light and no load. At heavy load it runs fine and I have the high speed mixture screw adjusted correctly. I also have the float adjusted correctly. I feel the reason it surges is that the idle fuel curcuit is not working.

If I manually push the governor linkage to idle (probably 1200 rpm) the engine stalls. If I let the throttle move open quick enough it continues running. I have tried the idle mixture screw from zero to 5 turns and everywhere in between and it makes no difference.

There is a welch plug right above the idle mixture screw. I am considering removing it to see if there is something plugged behind. Finding a new plug might be a problem so I would like more information before I go any further. I would like to find an old Walbro service manual that shows the fuel circuits and passages in the carb so I can try to figure out what's wrong.

The Onan service manual that I have only covers basic cleaning. Although I am a new member I have been looking at this forum as a guest for years and have always been impressed. This unit only has 435 hours so the carb shafts etc are in good shape, the electric choke even still works, so I want to try to fix it rather than replace. The service manual states that you are supposed to set the idle mixture at around 100 volts or 50 cycles which would be 1250 rpm. If I can't get it to idle at that speed it will never work right. I have the idle speed screw backed off enough to pull the throttle linkage by hand down to the 1250 rpm range but it stalls right away./QUOTE Be careful how you read that. The idle SET screw is supposed to be adjusted to give you 95-100VAC, not the idle MIXTURE screw.

If you mis-stated, then then I'm just blabbing, but if not, reset your idle mixture screw to about one full turn to start with. Make sure your throttle link is adjusted to the proper length, then start it and after warming up, adjust the set screw, then the mixture screw, then re-check the set screw. If all that works, load it good and adjust the high speed mix screw. Looking down on the carburetor body with the high speed mixture screw to the right you will see two passages that lead to the high speed jet area (where the high speed mixture screw enters). The inner hole which is the idle passage has a tiny hole at the bottom (approx.022 inch in diameter) which is probably plugged. On my LAU 7 I used a fine copper wire about.022 ' to gently clean this passage out and that solved the problem.

Once you remove the high speed mixture screw and the main jet you can see in there and as soon as you see the wire come thru you know you have removed the obstruction. I fought with this problem off and on for quite a while until I carefully examined the carb and attempted to blow out the passages with compressed air. The idle passage just would not come clean with multiple cleanings and compressed air.

My 5.0 BGA runs perfectly now. I am focuusing on your original comment that turning the idle mixture screw5 whole turns doesn't change anything. Since this is the case, I agree that the carb is still dirty.

Onan Engine Carburetor Parts

You didn't say HOW you cleaned it. I'd 'boil it out' with that carb solvent that comes in the gallon paint can that has a tray in it. In cases like yours, I strip a piece of stranded electical wire and take a individual strand or two to use to clean out any passages I can find. Also, you can try blowing low pressure air backwards through the idled screw hole. Here's my final secret, but you can't tell anybody on this website that dislikes Sea Foam: Recently I found a spray can of Sea Foam with a long thin plastic tube like you find on WD-40, etc. I stick the tube into the idle mixture jet hole and spray a bunch of the stuff in there. Let it sit a while and then do it again.

Leave the idle jet needle out and start the engine to, hopefully, suck in whatever is in the way. Pete Stanaitis.