Small Engine Troubleshooting Problems? Ask a Mechanic Now.
What is compression?Needs to be 150 psi.
When did it last run? If you put fuel direct into the cylinder, will it fire?
Fuel lines all been checked or replaced?
Exhaust been cleaned?
If all check out, I think you will find the piston scarred, remove the exhuast and look at the piston.
did you look at the piston when exhaust was off?
See if the rings have tension, you can push on them with scewdriver/
Do you have model with the compression release?
Could it be leaking?
Fuel lines correct?
No difference I assume! did you try it with the muffler off? How is fuel quality?