Tecumseh HM100 Backfire - Snowblower Forum : Snow Blower Forums
LinkBack Thread Tools
post #1 of 7 Old 02-18-2015, 06:37 AM Thread Starter
Senior Member
Join Date: Dec 2014
Location: Cape Cod, MA
Posts: 154
Post Thanks / Like
Thanks (Given): 5
Thanks (Received): 11
Likes (Given): 9
Likes (Received): 30
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.
bwright1818 is offline  
Sponsored Links
post #2 of 7 Old 02-18-2015, 08:28 AM
Senior Member
Motor City's Avatar
Join Date: Jan 2014
Location: SE Michigan
Posts: 639
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 44
Likes (Given): 0
Likes (Received): 50
Check the flywheel key. It may be sheared and the timing is now off. The symptoms are sounding like it.

Ariens ST11528LE
Honda HS720
Motor City is offline  
Post Thanks / Like - 1 Thanks, 0 Likes, 0 Dislikes
Thanks classiccat thanked for this post
post #3 of 7 Old 02-18-2015, 09:32 AM
Senior Member
Join Date: Dec 2013
Location: Massachusetts and Maine
Posts: 792
Post Thanks / Like
Thanks (Given): 3
Thanks (Received): 27
Likes (Given): 0
Likes (Received): 42
Flywheel key is a likely suspect...also may be time to decarbonize the head and check valve lashes. MH

1960 Ariens 45-10M
1961 Ariens 10M55
1977 Ariens 22000
1972 Ariens 10000
1990 Ariens ST724
1987 Toro 724
Murray Ultra 522
MTD Single stage
8 hp MTD hybrid plow
motorhead64 is offline  
post #4 of 7 Old 02-19-2015, 10:37 AM
Join Date: Feb 2015
Posts: 53
Post Thanks / Like
Thanks (Given): 5
Thanks (Received): 0
Likes (Given): 2
Likes (Received): 4
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
Rockadode is offline  
post #5 of 7 Old 02-19-2015, 04:55 PM Thread Starter
Senior Member
Join Date: Dec 2014
Location: Cape Cod, MA
Posts: 154
Post Thanks / Like
Thanks (Given): 5
Thanks (Received): 11
Likes (Given): 9
Likes (Received): 30
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!

Last edited by bwright1818; 02-19-2015 at 04:58 PM.
bwright1818 is offline  
post #6 of 7 Old 02-19-2015, 05:19 PM
Senior Member
classiccat's Avatar
Join Date: Mar 2014
Location: Albany, New York
Posts: 1,552
Post Thanks / Like
Thanks (Given): 177
Thanks (Received): 156
Likes (Given): 1636
Likes (Received): 381
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.
classiccat is offline  
post #7 of 7 Old 02-19-2015, 05:36 PM
Senior Member
Grunt's Avatar
Join Date: Nov 2013
Location: New Lenox
Posts: 1,962
Post Thanks / Like
Thanks (Given): 239
Thanks (Received): 281
Likes (Given): 2856
Likes (Received): 527
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.

Toro 8/24 (38080) 1989
Toro 721-QZR (38743) 2015 (Hemi Predator Power)
Toro 421-E (38585) 2008 (New Owner)
Experience is something you don't get until just after you need it.
Grunt is online now  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Snowblower Forum : Snow Blower Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome