I have an older snow thrower with an 8 hp B&S engine. For the past couple of years it would occassionally backfire while running - sometimes shooting sparks or flame out of the exhaust - but it always ran. This year it won't run. I took the carbuerator off, went through that, blew it out etc. but it didn't help. It won't start at all even with choking but if I put a little gas under the plug is might run for a few seconds (after several pulls) but runs very rough, backfires several times then quits. Any suggestions?

Sheared Flywheel Key, Easy Fix, Pop The Flywheel And Replace

yeah the key's shot. easy 2 dollar peice and 5 minutes out of my time to fix. might take you more but its easy.

Definately a flywheel key. It has probably been partially sheared for the past few years and now it just suddenly broke free.

Thanks for the advice. Everyone pointed to the flywheel key so I took it apart this afternoon...took me a little longer than five minutes but the next time it won't!!!

Replaced the key and it works great.

Thanks for the helpful advice...

yep thats how easy it is. simple and its always the problem when the engine misfires or runs rough from no carb problems.

hehe i was right im not stupid am i scott?

One thing to remember and the flywheel key will cause it, if fire comes out the muffler and there is not a rich condition with the carb, fire has to be going by the ex valve. The flywheel key is the first thing to look at if it is ok I have found a burnt ex valve or it is not seating and a valve job took care of it. If it backfires out of the carb the intake valve is letting fire pass by. If you do a lot of repair work a leek down tester is a good investment. Mike