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Discussion Starter · #1 ·
Hi,

First time posting on this site and I'm hoping I might be able to find some suggestions. I recently inherited a snapper snowblower with a tecumseh ohsk55 engine. It had been sitting for about 10 years and was in desperate need of some love. It wasn't running at first, but after replacing the carb, fuel lines, fuel, and oil it now fires up on first pull. As soon as I take it off choke it surges bad enough that the linkage between the carb and governor arm pops off the carb. I replaced the governor-throttle spring thinking it might have been worn but still having the same issue. If I hold the governor arm it stays running, although a bit rough and I also noticed a white foam starting to come out of the breather tube after a while (photo). Any thoughts? Any help would be appreciated. Thanks in advance!
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The surging caused by a clog in the idle/slow jet circuit.
The white foam coming out of the breather tube is from moisture condensation in the crankcase/oil from sitting for a long time.
When the engine is run it will mix with the oil and produce the white 'Foam' as it is leaving the breather. You will have to run the engine for an extended period of time to get it hot enough to 'Boil' out any remaining condensation that collects inside the engine and ends up in the oil itself. It is a normal occurrence with engines operated in moist environments like snowblowers.
That can happen even after you change the oil an add fresh oil to the engine because the condensation is present all over the inside of the engine from sitting for an extended period of time. That is moisture that condenses out of the air.
After the engine is hot and shut down, when it cools, it creates a vacuum and draws air back into the crankcase, and that air has moisture in it.
A lot of times there should be a tiny spring on the throttle plate to governor arm along with the linkage rod that keeps tension on the linkage rod. It usually wraps around the rod and hooks into both ends of the plates that the rod connects to also to help it from coming out of the holes it is mounted into.
 

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Take the black plug off (bottom center of first photo) and screw out the idle/pilot jet. Put a wire in it to make sure it isn't plugged up. Sometimes I open them a few thousandths to solve the hunting issues. A good ultrasonic carb bath wouldn't hurt either but it looks like a fairly new carb on there.
 

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When you replaced the carb, did you purchase a "lower priced" knock off, or did you purchase a little more expensive carb?
Did you research the carb to ensure it was the correct carb for our application? Check engine model number and parts list, or just purchase a carb listed for "a snapper snowblower with a tecumseh ohsk55 engine?"
Did you replace the carb to intake gasket when you installed the replacement carb?
If you apply partial choke does it run evenly, or continue to surge?
 

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Discussion Starter · #5 ·
Thanks for all the feedback everyone.

That makes sense about the "foam" @ST1100A . I also suspected there may be a clog causing the surging, but thought with a new carb that shouldn't be a concern.

@3vanman - it was a cheaper carb so may be a lesson learned there. I did replace the intake gasket. It runs OK on partial choke, but still a little surging.

I plan to try @KennyW in CT 's suggestion with the idle screw and if that doesn't work I'll clean up and reinstall the original carb to see if that fixes the issue.
 

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Not necessarily this will solve the surging but any carbs bought should be adjustable, adjustable low and high fuel mixture screws.
 

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Whenever you buy a replacement carburetor you should always open it up and thoroughly clean it out internally including all the jets, especially the slow jet because 9 times out of 10, it is blocked from new and many times the carbs are sprayed with a finish preservative coating to protect the metal from corroding and that will clog things. Even O.E.M. carbs are like that from new.
You want to do that to any replacement carburetor you ever get before you install it on your engine or you will be having problems with it like 'Surging' when new.
Most of the slow jets on the 'Cheapo' replacement carbs don't have the slow jets drilled out properly for enough fuel to flow through them in the first place and need to be enlarged ever so slightly, that is a 'Quality Control' problem with them to keep the prices low, another thing that is 'Non Existent' with Chinese products.
 

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The offshore auto parts industry isn't referred to as C.R.A.P. (Chinese Replacement Auto Parts) for nothing, and the same applies here. Carb cleaning is far too quick and easy to not be the first try in most situations . . . replacement carbs, beside the potential QA issues likely are not jetted for cold weather use . . .
 

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The offshore auto parts industry isn't referred to as C.R.A.P. (Chinese Replacement Auto Parts) for nothing, and the same applies here. Carb cleaning is far too quick and easy to not be the first try in most situations . . . replacement carbs, beside the potisl QA issues likely are not jetter for cold weather use . . .
I work on a large number of snow blowers both repairing/rebuilding carbs and replacing them. Yes, some of the "bargain" brand (non OEM, $15 carbs) are not of the highest quality. That said, I regularly "bolt on" carbs from non OEM suppliers with little or no issues, some will need fine tuning, less than 1% have caused me any grief.
Carbs come from Brazil, China, Japan just to mention a few places.
 
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