Craftsman Snowblower only runs on choke

tjm0852March 29, 2009

So my craftsman model #536.881800 snowblower was only running on choke. As soon as I switch it over to run it would stall. I noticed that the bar to govern would engage and kill the engine. This started during this snow season and I want to get it fixed before I store it this year.

I removed the Carb and cleaned it up with carb cleaner, but that has not helped at all.

After I pulled the carb it would not start at all, so I pulled the spark plug out and put a tablespoon on gas in there. It started up but will still only run on choke. Spark Plug looks good and was replaced about a year ago.

There was no varnish in the carb and the gas is fresh and it has always been stored with fuel stabilizer in it.

It has a Briggs and Stratton carb with the number 21473 stamped on it. Anyone have any suggestions?

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your carb main jet is clogged...

pull it again and use guitar wire, welding tip cleaners or something similar to get in there and open the main jet/idle jet.

on some carbs its a little brass dude - which can be unscrewed from the carb body and thoroughly cleaned.

because its clogged - you can only keep your engine running on the choke circuit. as soon as you open up that circuit your engine will idle again.

While your at it do yourself a favor... put in a fuel filter and a fuel shut-off valve. when your done with the unit for the season - run the engine and close the fuel shut-off valve - letting the engine empty the carb.

Happy trails and good luck - Dave

    Bookmark   March 29, 2009 at 7:36PM
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I imagine the main jet is the largest one (brass tube) that goes from the bottom of the carb fuel pick up area into the main chamber where the flaps are, right? I can clearly see light through it, carb cleaner flows freely through it and I can blow air through it. I have cleaned it out with a stiff wire. The other small pin holes do not appear to be clogged and I can get carb cleaner to drip through as well. I am approaching the point where I am torn between buying a whole new carb or bringing it to someone to have them fix it. The latter is not so easy when I have nothing to transport the blower in.

    Bookmark   March 30, 2009 at 1:03PM
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I assume you are using compressed air to ensure those ports are clear. It is important to force any debris out of the carb that you may have in it.

also when re-assembling make sure your intake manifold gasket (if that applies in your case) is not leaking.

another tip for you - two of the mowers I have, have a small brass spring loaded valve which can be easily pressed to bleed out water and small debris from the carb, and ultimately the fuel line. I love these little dudes because they make cleaning (and emptying ) out the float bowl of water and debris so fast and painless.

I get a lot of water in my gas cans and eventually my gas tanks - so I generally press the little brass button about once a month to bleed the bowls. I can tell when the carb needs attention when my engines wont idle well. I generally assume I dont have a clogged main jet as all my equipment has fuel filters.

By chance - have you emptied your fuel tank ensuring that you dont have any water in your system ?

When I'm not sure about the fuel Im using ... I dump about a quart.5 into a cleaned juice bottle and let the fuel settle. From there I can see any water (at the bottom) in the clear jug, and I can dump some clean fuel into my tank and know Ive not introduced any water into the system. Especially important while your trying to diag a sick engine.

Occasionally I will drain a tank and fuel line - and leave the gas cap off for a day or two - allowing the tank to completely dry out... (while im working on the carb). This step is best left for a warm day or two in the sun. The tanks will dry out very quickly.

Good luck.

    Bookmark   March 30, 2009 at 7:54PM
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Same issue with my sowblower, it will only run smooth on partial choke. No choke and the engine surges, runs rough. cleaned the carb 2, replaced the needle seat and still runs rough. this carb doesnt have any adjustments. 8hp Briggs OHV engine 2006. any other ideas?

    Bookmark   March 30, 2011 at 4:28PM
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