Small Engine Troubleshooting Problems? Ask a Mechanic Now.
If you remove the spark plug and ground it, do you have spark? With spark plug out, put finger over the spark plug hole and spin engine to see if it has enough compression to move your finger. If it has spark and compression, put a teaspoonful of fuel into the spark plug hole and see if it will fire for a few seconds.
If it does not fire, the timing may be off, and the flywheel key to the crankshaft needs to be checked.
Did you find the problem?
Do you have spark? Do you have fuel to carburetor?
Fuel in muffler is caused by the carburetor leaking fuel through the needle valve and float. It also will let gas enter the crankcase. Repair would be replacing the needle valve or replacing the carburetor.