Tecumseh HS50 spark issues

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Old 11-23-13, 06:03 PM
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Tecumseh HS50 spark issues

I have a Topflite (MTD) Snow thrower model number 310-600-120. Powered by a Tecumseh HS50. Got it from an auction. Brought home. Put in fresh gas, new plug. Pulled it a bunch, and wouldn't start. Sprayed ether, and it ran! So, took carb cover off, found broken spring on throttle. Went to pull it again, recoil broke. Now, wait a week for the recoil to arrive, so I painted a few areas, greased some stuff, etc. Now that I have a recoil back on it, spark is hit and miss. I am using a bulb type in line spark checker. Seems that the first pull, I have spark. Second pull, nothing. Kind of wondering how my electrical system works on this model but MTD's website has been no help on a manual. I have a small switch-looking thing under the carb with a wire that runs into the engine shroud, and another that runs to the key switch. This is the only wire that runs to the key switch. The switch looking thing that is under the carb did get spray painted... did i paint something that had to be bare for proper connection?? Any help is appreciated. just got the first snow that stuck and I'm gonna need this soon as my plow truck refuses to cooperate.
 
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Old 11-23-13, 06:17 PM
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If yours is new enough to have the anti backfire solenoid on the bottom of the carb, then you should have electronic ignition. On those, check to be sure the air gap between the coil and flywheel magnets is .010". If so and still no spark, unplug the kill wire from the coil. If still no spark, the coil is bad.
 
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Old 11-23-13, 07:03 PM
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sorry, I should have been a little clearer. This seems to be a sort of switch that mounts to the engine cover. It has a wire coming out of the top, with a loop on it. When the throttle is moved to the stop position, an arm comes down and touches this wire with the loop. Out of the bottom of said switchy thingeroo there are two wires; one to the key switch, and one that i assume heads to the coil as it goes under the engine cover.
 
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Old 11-23-13, 07:37 PM
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Oh, okay, now it makes sense. I couldn't remember ever seeing an anti backfire solenoid on one of those engines anyway.

On that engine, you'll probably have to clean the points. They are under the flywheel under a little stamped cover. Don't loosen the bolts or screws that hold the coil and plate on the engine. Getting this reset properly requires the use of special tools and an involved procedure. Just clean the points with an emery board and see if you get good spark.
 
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Old 11-23-13, 08:00 PM
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For what it's worth my MTD blower had the HS100 engine with a spark problem.
I removed the recoil cover, cleaned the rust buildup from the magnet on the flywheel and the underside of the pickup coil , put a thin coal of dielectric grease on both. Reassembled everything and bam -- starts first pull every time.
 
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Old 11-23-13, 09:21 PM
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I see. This does make sense, as I am fairly sure this thing sat outside at the auction yard for some time. I'll try that in the morning.
 
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Old 11-24-13, 04:47 AM
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I see. This does make sense, as I am fairly sure this thing sat outside at the auction yard for some time. I'll try that in the morning.
That --- and the rust buildup occurs over time---- remember it's an outdoor engine .
Also, it's a snow blower , snow gets into all the nooks and crannys and melts on the warmer flywheel will rust things.

The other bits of parts you painted have to do with grounding out the spark voltage to shutdown the engine. The wiring is connected to the *key* and to the *off* position of the throttle lever.

Without the *key* inserted the contacts close and grounds the pickup coil --- insert *key* opens the contacts.

When throttle lever is in the idle or full position the contacts are open. Move the throttle control to *off* closes the contacts and grounds the pickup coil.

The paint is more likely to prevent shutting down -- or -- grounding the pickup coil. Since the paint is more of an insulator than a conductor.

The spark plug itself should be changed as well. Worst case is the spark plug *wire* insulation could be detriorated and leaking --- which means changing the whole pickup coil.
 
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