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Hi all, Sorry if this has been addressed somewhere else, I wasn't sure how to search for this particular problem. I got a Briggs and Stratton 6hp 12V802 on a lawnboy mower the other day and while trying to get it back running I'm hitting a snag. Replaced the air filter, air intake manifold (was cracked in two), cleaned the carb, and put fresh gas in.

The engine spins freely and will even run (but poorly) once in every dozen or so pulls for a few seconds, but about 1/3 of pulls result in what seems like either the engine trying to spin backwards or it trying to pull my shoulder out of it's socket very abruptly about 1/2 way through the pull. I've never come across this before but after replacing the pawl teeth and retaining piece in the pull starter it's still doing this and I think it ?might? have something to do with the engine not running as it should. That or this mower has gremlins.

Any ideas?

Sound like a broken flywheel key. Not hard to check and or replace.

And that would be able to make the engine try to go backward like that? From the spark timing being off I assume?

Yep, it's sheared. I've tried the prybar and hammer on the flywheel nut method of pulling the flywheel, but it really seems wedged in place. Any suggestions for gettng it off?

Yes. I've repaired many with your symptoms. Usually end up elbow in my gut from pulling.

Either a puller or hammer on the nut with prybar applying up pressure. Looking for shock hit so one solid whack usually does it.

If you are using a 16 ounce hammer put it back so you can find it to drive nails. To remove flywheels using the hammer method a 3 lb. hammer will work with a sharp smack but I like a 8 lb. sledge hammer squarely dropped from about a foot .

Flush the nut with the shaft end and use a nail bar etc. to just raise the shaft the thrust distance . Since we aren't trying to pry the flywheel off but are just lifting the shaft and flywheel, about 5 pounds pressure on the end of the bar is plenty .

SandburRanch said:

If you are using a 16 ounce hammer put it back so you can find it to drive nails. To remove flywheels using the hammer method a 3 lb. hammer will work with a sharp smack but I like a 8 lb. sledge hammer squarely dropped from about a foot .

Flush the nut with the shaft end and use a nail bar etc. to just raise the shaft the thrust distance . Since we aren't trying to pry the flywheel off but are just lifting the shaft and flywheel, about 5 pounds pressure on the end of the bar is plenty .

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Thanks. Didn't feel like typing all that.

I agree with the sheared FW key, but if by chance it is "not" sheared, check your valve clearences. I have found some briggs tend to pull back due to "too much" play in the valve adjustments and not allowing the compression release to operate.

Thanks guys! I've went ahead and borrowed a gear puller from a buddy of mine. I'm headed off to get a new key for it now. Damn thing jumped about 3" off the shaft when it finally gave way. It was offset about 1/4 turn around the shaft from where it shouldhave been.

Okay, so after a replaced flywheel key, intake manifold, adjusted carb spring, cleaned carb, rebuilt pull starter (which in retrospect I might not have needed), and lots of assembling and disassembling this thing IT'S WORKING!

Thanks for pointing me in the right direction, and if I may say, getting a gear puller to pull the flywheel worked so much better than trying the hammer method, and was much less hair raising. Need to do a little adjusting and put a new blade on it, but she'll mow another yard now thanks to you guys!

I'm done wasting my time. I said to leave the nut on the shaft.

Did that fix your problem?