my 6.25 hp Tecumseh was acting poorly all last year.
I have run into an aluminum downspout , but it had picked up and kept running --till this year.

I had sharpened the blade but did not tighten it enough. The blade came loose and the mower stopped working.

The mower would only backfire .

After checking here and other places the broken key problem fit the situation.

I checked the blade key, it was not fully sheared just partly so I changed that $10. Then I changed the flywheel key 80 cents. my puller did not work so I gingerly used a crow bar to leverdge up the flywheel about 2mm per rotation till it poped off. I then torqued the flywheel nut down 40 lbs feet to squish the key back into the flywheel

sucess feels good .. :thumbsup:

WOW runs like new !!! and saved about 200. in repair costs

congrats!!! and now that you have a little knowledge you can make a few bucks doing the same fix for someone else as its a pretty common problem. f-n-m :thumbsup:

If I had a known about this I woulda bought this little sucker

for Sale:
6.25HP Tecumseh gas lawn mower
Large back wheels
Includes rear bager, side discharge and mulcher
3 years old...used 2 seasons
Canadian Tire sells for $399 plus tax ($458)
Motor kicks back and won't start.
Colapsible handle, foam grips and safety bar.
New oil change.

Like new. $100 non-negotiable.

fixed it for 25 bucks and had a mower for a few years :rolleyes:

yeah, i left an answer a while back in the thread for tec manuals, but when they stop very abruptly, going at 3200 or 3600 rpm, the keys will shear most or all of the time..... but very easy and cheap to replace, not that a small engine shop will cost severely, maybe 20 bucks at the most they should charge for the key replacement.