onan carb part two

bdunegan

Member
Once again back to square one. As advised, I took carb apart, and soaked it, cleaned all passages and jets good , made sure all was clear, used Dremel tool and polished inside good removing all trace of oxidization, let soak somemore, cleaned jets again, put together with all new gaskets. Put 100% gas in it along with some atf as suggested. Started up and ran perfect. Drove it around, and killed it and restarted about a dozen times, ran great. Today mowing, it ran perfect and mowed fine for about an hour, then surging badly once again. I have had it, it is in oklahoma just south of tulsa, and going to be for sale cheap. It is a 520H with 800 hours, 48" deck, forward swept axle. I am done with it!
 
Does it have the intake manifold like this? Strange things happen when they get warm, mine was leaking in the seam where the two halves are put together...causing surging and rough running.
a165005.jpg
 
Mine is basically the same. Onan engine with Nikki 6200 carb. I think the halves of my manifold actually have screws in them to tighten. What would be the fix, new manifold or possibly just gaskets?
 
After it cools down, it still surges. Unfortunately it is the non adjustable carb. Once it throws it's fit and starts surging, it does it every time it is started. I used to be able to smooth it out with choke, but since this last effort, choke don't even help. Least of bit of choke applied, it puffs black smoke and sure enough floods. I know I have had it with this thing!
 
I should have a manifold I could send you. Let me know what engine you have. Model and serial number. I will see if I can find the PSB on it.
 
Just remembered. I had one down here. Would run fine for a half hour. Then went nuts. Found the intake manifold gaskets were bad. Replaced them solved problem. Might be some thing to check.
 
The model # is P220G-I/10955G. The serial # is K963611721 and P/N 94-1811. It has a Nikki 6200 carb on it also
 
Just went out and started it again after setting all night. Same thing, surging badly, and no amount of choke helps. I was able to spray carb cleaner around seams of intake, and where it mounts to block, and no change at all. What am I missing? And I was wrong, my manifold isn't screwed together, it's rivets. Must have been on the old one I had. Am still willing to try different manifold with different gaskets tho. Would really like to get this thing figured out. It mows great, when it's running and is very heavyduty.
 
bdunegan

the 6200 means NOTHING.

you need to list the 146-0xxx # from the side of the carb.

a 1996 will likely have the 146-0698 emissions carb. ( a piece of junk )

thank you. boomer ( the used onan engine parts guy, also NOS and new )
 
I'll have to wait till I take carb off again to get numbers, and I'll agree, whatever carb it is, it's junk!
 
Thank you for checking anyway! Where is a good place to get the gaskets for the manifold. I am going to take it down one more time when I get gaskets, and split my manifold and reseal it, and if that don't do it, it's junk.
 
Ebay has them show up at times. On smokstak we have a guy called Onanparts. Jacks small engines should have them
 
Just got back to carb. Numbers is 140-0598 carb. Is this epa carb? And knock on wood, I took covers off today and was squirting carb cleaner on all seams and manifold gasket and no change, still surging. I let it idle, and it died. I forgot to turn gas on. I turned it on and started it up, and no surging at all, choke off. Drove it around about 30 minutes with pto engaged, slow throttle to wide open, and no surging at all. Could it be possible that needle valve was sticking, or had piece of trash on it?
 

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