Tecumseh HM100 Backfire - Snowblower Forum : Snow Blower Forums
 
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post #1 of 7 Old 02-18-2015, 06:37 AM Thread Starter
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Tecumseh HM100 Backfire

I have an Ariens ST 1032 with the HM100 on it. I forget the exact model number; but this one is black, has the engine-mounted throttle, primer on the blower housing, small recoil handle and as I recall, POINT and CONDENSER ignition. The last time I tried to start it, it ripped the starter cord out of my hand a number of times and even backfired so bad that I lifted the whole back end of the whole machine off the ground with the starter cord! Sometimes it would try to run intermittently. Once it finally fired off, it ran great for the whole, wonderful snowblowing experience. Ideas?

Last edited by bwright1818; 02-18-2015 at 06:39 AM.
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post #2 of 7 Old 02-18-2015, 08:28 AM
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Check the flywheel key. It may be sheared and the timing is now off. The symptoms are sounding like it.




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post #3 of 7 Old 02-18-2015, 09:32 AM
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Yeah,
Flywheel key is a likely suspect...also may be time to decarbonize the head and check valve lashes. MH

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post #4 of 7 Old 02-19-2015, 10:37 AM
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While you're in there check the points and service them , slip a piece of sandpaper in between and make sure the contacts are clean, blow the crap out and throw a dot of grease on the felt so it gets circulated around the timing lobe on the shaft. Set gap as necessary.

The backfiring can be from lean condition too, maybe plugged jets in carb, run some seafoam in your next few tanks of fuel if you don't want to do a carb rebuild and see if it improves
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post #5 of 7 Old 02-19-2015, 04:55 PM Thread Starter
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I like all the ideas. They all make sense. Unfortunately, this means I must have screwed something up, if one of these ideas is the cause.....because I already did all that stuff when I first got the machine. But hey, I am 58 so dementia is setting in, ha ha.

When I first finished the machine and tested it, it ran okay, started okay. After I finally start it now, it also runs fine. It just starts something from a Steven King book.

I will have to wait to get back and check things out. A day after my last run of the machine, my back went out and a recurring tendon problem came back in my hand. Gee, do you suppose it's because the entire back of the machine came off the ground during numerous back fires, suspended only by the pull cord I was holding??? LOL. Thanks very much for all the replies!

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post #6 of 7 Old 02-19-2015, 05:19 PM
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You may not have torqued the flywheel nut enough....From what I understand, one of the leading causes of broken keys on a snowblower engine.
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post #7 of 7 Old 02-19-2015, 05:36 PM
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Kick backs are not a pleasant experience. You could try slowly pulling the recoil until you feel compression, let the rope rewind, then give the rope a good hard pull. If your lucky, the engine will start with no further physical injury.

If your engine is equipped with an electric starter, use it when possible. If not equipped, you may want to kook into adding one, mostly for cold starting the engine.

As previously noted, if you worked on the points in the past, did you torque the flywheel to specs? Although pretty rare, a sheared flywheel key is possible.

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