Outdoor Power Equipment and Small Engines - SnowBlower Backfire Under Load

Hi all,

I am having the exact same backfire, nearly stalling under load problem with my 1996 Noma Snowblower with a 12 HP Tecumseh motor. I have done all the suggested fixes, with the exception of the main jet adjustment, already mentioned with the except of getting the rebuilt kit for the carb, only because I don't know what kit it is because there are so many kits. I know this is meaningless but the motor on this blower looks factory new, the carb was immaculate when I pulled it but I still cleaned it and blow it out with air. Still no luck. Anyone have any other suggestions because my next step was a sledge hammer and credit card to buy a new blower.

Thanks much

Ed

I moved your post to a thread of its on. Tagging on to another post causes confusion.:thumbdn: Post the model and spec number of your engine and the part number of the carburetor kit you used. With this, we can better help you with your problem and confirm you have used the correct kit.

Thoroughly cleaning a carburetor requires total disassembly, to include Welch plug removal.

Here is a link to a document that may help:
http://www.greenindustryeducation.com/landsexpo/exhibits/Tecumseh.pdf

You said you cleaned the carb. How did you clean it? Did you soak it? You need to soak it for an hour in carb cleaning solution. Spray carb cleaner does nothing. Soaking gets into all small pinholes of the internal portion of the carb. Being a 1996 model, means it is a fixed jet. the carb kit you need is 631021B. This kit contains needle, seat and float bowl o-ring.

Thanks, I did soak it for a couple of hours but didn't pull the welch plugs. I did notice a small section of oxidation on the float that I scrapped off. Lastly a fixed jet means I can't adjust it? Sorry for the ignorance. I know enough to be dangerous I guess.

Well the northeast got hammered with snow again and my snowblower is still not working. I do have details now however. The engine is an OSK120, the carburetor is 632536. The blower starts on the first pull. It idles ok with an occasional spudder. The I engage the auger and drive system it runs fine but as soon as it hits snow with a little load it starts running extremely rough, it backfires and dies. I Tried it with part choke and it ran like that for a short period of time and now it doesn't run with or without choke. Even when hot I have to put the choke on for the first pull and then close the choke to start it with the second pull. After it starts now, it runs very rough for about 25 seconds and then stabilizes until it enciunters snow. So I only question is if this is truely a carburetor issue or could there be something else at fault. Thanks for all the help, Ed.

Just a tip for these machines since they sit for long periods. Always start the engines up on regular intervals, change the oil about every 4-6 months regardless of usage.

I never drain my tanks, carbs on whatever machines I own...leaf vacuums, snow throwers, chippers, chainsaws, whatever.

Storing IMO is bad for extended periods, just take 5-10 min and fire them up, keep fresh fuel in them and run some Stabil if needed but you don't have to really.

You don't need the snowthrowers often, but you need them to work when called upon. Just some food for thought, not trying to flame the post but as far as a backire under load....drain the tank and run some BG 44K in the fuel to the recommended mix, will help to remove some deposits from the valves.

Sometimes a little grit gets into the jets, sometimes a little time of running may clean it out. Get a fresh plug, fresh fuel, some 44K and let it run fast for awhile.

Don't use Exxon fuel, don't want to go into that. Use either Chevron or Shell, don't want to get into that either.

Try it and report back.

When you soaked the carb, did you soak the main jet & verify all the holes in it are clean?? You may also try a new spark plug to be on the safe side...Roger

I soaked the entire carb for several hours and blew out all passages. I did not however remove the welch plugs. I used fresh gas, 87 octane with stabil added to it. I just ordered the rebuilt kit for the carb, will get a replacement plug and see if that helps.

Hi again,

I finally got around to removing the carburetor, again, and soaking it, again, and installing a rebuilt kit on it. This time I removed the welch plugs and noticed that under the smaller of the two plugs the pin hole was damaged and is now much bigger than a pin hole. I reassembled everything but have not reinstalled the carb yet. Is the damaged pin hole rendering the carb inoperational?

Thanks again

Ed