Tecumseth Snow King engine - backfiring

Old 11-08-01, 12:06 PM
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I have a 10 hp engine on a Craftsman snow thrower that starts OK but backfires occasionally. Sometimes, as it's shutting down flames shoot out of the exhaust.

What do I do to fix this.???
Old 11-08-01, 02:13 PM
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Engine Timing, Carburetor and or Air Fuel Mixture

Hello and Welcome bill maz to the Do-It-Yourself Web Site and my Small Engine forum.

If the engine timing is correct, the flywheel has not been removed, etc. chances are the engine timing is fine. Unless the machine encountered something that cause the engine to come to an abrupt stop which may have altered the timing.

Another possibility may be a restricted carb or a flooding carb. Check the fuel adjustment settings.

Within the archives of this forum are other postings on this topic and the replies to help determine the cause and suggestions for the remedies.

An excerpt of one of many prior postings is below for your convenience. Pick and choose the parts that apply to your engines current conditions.

Regards and Good Luck,
Small Engine Forum Moderator
"Accurate Power Equipment Company"
Small Engine Diagnostic Service and Repair Technician.
Personal Quote:
"If it ain't already broke, don't fix or tinker with it until it is broken!"
Bare in mind my company no longer services nor repairs small engine powered equipment. The information provided is accurate to the best of my knowledge.


Most likely cause for an engine to be hard starting, running rough, backfiring, accelerating poorly, running hot, stalling at idle, dying out at top speed, etc. is a fuel mixture set too lean.

If your machine is experiencing any of the above engine problems, try riching the fuel mixture for both low speed and high speed. About an 1/8 of a turn counterclock wise on the left {L} fuel screw and 1/4 turn out on the right screw {H}

Also check for a restricted fuel supply. This can range from fuel flow from the tank, through any inline filter, low fuel level in carbs with fuel bowls or a restricted carb of either bowl or diaphram type. Try using fresh fuel to flush out any stale fuel while checking fuel flow from the tank.

Check the spark plug. Be sure it's the correct heat range plug for the engine. A plug that runs too hot can cause minor lean burning.

Check the air filter. A dirty, clogged or additional wet paper air filter can drastically restrict air flow causing an excessively rich fuel mixture, rough running, carbon buildup, fouled spark plugs and black exhaust smoke.

Also check the muffler for good exhaust flow. A damaged, overly rusted or excessively carboned up muffler may have internal damage causing an exhaust restriction. Exhaust restrictions can cause several problems. Overall poor engine performance, excessive engine heat, failure to accelerate properly, hard starting, rough running and many more.

Other possibilities could be engine timing, especially if the flywheel was removed prior. Incorrect valve settings, an overly rich high speed fuel mixture {which would produce black smoke} or an engine running too hot caused by a lack of air cooling.
Old 11-10-01, 03:43 AM
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Other thoughts,...the flywheel key could be bent enough to allow it to run but throw timing off and cause your problems. Plan to replace key nomatter what you find when you pull flywheel. Removing the flywheel can be tricky. Use a tool made for the job. Hammer should not be an option. Also valves may need adjustment or they could be burnt. Valve adjustment requires removing valve from engine and grinding stem. This job may be better left to experienced person unless you are comfortable in removing cylinder head and pulling valves. Good luck and take care.

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