I have a murray lawn tractor and I hit a rock with the blade the other day and it went off. Now the tractor starts and crank but the engine doesn't turn over. It will start initially but the engine doesn't say on but for three seconds before going off again. Does anyone have any ideas, help?

You might check your flywheel key and see if its sheared.

you might check your flywheel key and see if its sheared.

That is the best place to start sheared key can cause all kinds of starting issues .