QuestionThis started off as a single occasional backfire. Now I can not start the lawn mower engine at all. The kickback will yank the starter rope right out of my hand. The carburetor is clean and snugly mounted. Air filter is clean. The gas is a bit old. The lawn mower is maybe 3 years old at most. The power was a little low when it ran last week. I get a little puff out the exhaust and a little puff out of the carburetor. What's up?
AnswerYou either have a sheared flywheel key, a loose blade, or gas in your oil.
Remove the spark plug. Tilt the mower so the spark plug hole is pointing/facing up, toward the sky. Make sure the blade adapter is not cracked and the blade is super tight.
Tilt mower back down, with spark plug still removed. Pull string as if you are trying to start it. See if any fluid squirts out the spark plug hole. If so, does the oil smell like gas? If so, drain oil, refill, and replace carburetor inlet needle and seat.
If the above are good then check the flywheel key. You will need to remove the top engine shroud to gain access to the flywheel nut. Remove nut...we use an electric or air impact gun to remove. See if flywheel key way and crankshft key way are lined up. If not, the key is sheared.
Let me know what you find.
Eric
