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PK., Small Engine Technician
Category: Small Engine
Satisfied Customers: 1052
Experience:  Retired Owner of a full service shop and national parts sales website.
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just rebuilt carb on 8 hp tecumseh snow blower. Surges

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just rebuilt carb on 8 hp tecumseh snow blower. Surges
Hi, can you give me some details about what you did with the carburetor? Did you replace the needle and seat, adjust the float, etc.? Also, what's the model and spec number of the engine?
Customer: replied 7 years ago.
replaced the needle,bowl gasket,new main jet and idle adjust. Did not replace seat. did not adjust float. Set initially at 1 1/2 turns out on both main and idle adjust. Set idle stop at 1 1/2 past contact with throttle plate. Continues to surge. It is on a 26" snowbird snow blower.
Customer: replied 7 years ago.
ser 9227D

Did it have a Viton tipped needle, like a rubber tip, or was it solid metal? And what material is the seat?


The float must sit level with the base of the carburetor when you turn the assemble upside down. Did you check for this?


Surging can have several causes, poor intake seals, loose head bolts, leaking head, malfunctioning governor, poor governor spring tension, poor carburetor air flow, and others.


The thing to do is start with the cheapest, simplest and most obvious. That would be the float level if you couldn't adjust the mixture screws and eliminate the surging.

Customer: replied 7 years ago.
I did not check the float level. It also runs better when the choke is partially closed. It is an all metal needle. Is there a diagram on how to check and adjust the float level?

If it has an all metal needle then it should have a neoprene seat which has to be changed. I use an awl which I put a slight hook into the tip of for pulling the seats but any slender stiff wire will work. You pretty much have to replace the seat when replacing the needle if it does have the neoprene seat.


For checking the float, all you have to do is turn the carburetor upside down and see that the float is parallel to the base of the carburetor. There should be an even gap all the way around it. If you have a metal float, you can bend the little tab where it contacts the needle to adjust it. If you have a plastic float and it's off kilter even after replacing the seat let me know and we'll go from there.


One other thing I would ask is when you rebuilt the carb, how did you clean it?

Customer: replied 7 years ago.
I did not see a neoprene seat. I will check the float. I cleaned it with some mineral spirits and sprayed some ether through it as well.

Customer: replied 7 years ago.
It is a metal float.

Mineral spirits work well for cleaning carburetors. Especially if you soak it for an hour or so. Then rinse with water and blow out with air.


The engine will have a model number, like HSK40 or something similar and a number after that. Can you give me those numbers?

Customer: replied 7 years ago.
I am going to take it off the machine again and check the float and take a closer look at the seat.I adjusted the float . I am getting gas in the bowl but now when I prime it I get no priming gas and it looks like I am not getting any gas up through the high speed jet.

Ser number hm80155127F 9227D

Customer: replied 7 years ago.
You will not believe what I found. During shipping of the rebuild kit. The neoprene gasket for the needle valve got stuck in the main jet. It fit perfectly but was restricting flow. When you told me about the neoprene gasket for the needle valve I recognized what had happened and removed the misplaced gasket. It runs OK at high speed<a little rough with an occasional slight backfire, but I can not get the idle adjust right.
Customer: replied 7 years ago.
Thanks for your help. We bought some land near Telluride ( I assume your shop is in Grand Junction,Co.) and hope to retire there. Living in Cleveland now. Trying to get things ready for the winter. Expect payment after your next response.

I'm in Tennessee, but everybody assumes Colorado.


To adjust the carb so it runs smoothly, turn the main mixture screw out 1 and 1/2 turns, crank the engine, set the throttle to your normal run speed and then slowly turn it in until the engine starts to run rough. Then back it out until it runs smoothly and then rough again. Then set it at the halfway mark of where it ran began to run rough. The trick is to turn the screw extremely slowly. It should take a couple of minutes to go from rough to rough.


Then set the throttle to allow the engine to slow idle and do the same thing with the idle jet, the one on the side.


If it's backfiring through the carb then it's running a little lean and that needs to be corrected as you can damage the engine from overheating.


I suspect winter is pretty close to Cleveland about now. Thanks and let me know if you need anything else, PK.

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