I have a 2000 yard machine riding mower with a briggs and stratton engine. I have used this mower several times this season. My son was cutting the grass the other day made one pass and the mower stopped working. Tried to restart and the shaft and pulley just spin.
Have checked the carb, gas, and changed the spark plug and magneto. I read on one web site to try putting a teaspoon of gas behind the spark plug and still not starting. There is a spark from the spark plug but won't start. The rockers are moving but not for sure if the piston is moving. Have been from one end to the other on the wiring and everything seems to be fine.

Please help

Thanks sklavos71

Did he hit something. If he did then check the flywheel key.

The flywheel key is my guess. If they have fuel, and spark, the only two things they need is air, and compression. The problem is that the spark they have may not be at the correct time. This is caused by the flywheel key being sheared. Remove the top engine cover, and "chopper" screen, remove the flywheel nut and see if the flywheel key is intact, I think this is where the problem is going to be found.

Thanks That Was The Problem