Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!
If you put a teaspoon of fuel direct into the spark plug hole, re-install the spark plug , will engine start for a few seconds, or does it continue to backfire? If it does not try, and keeps backfiring, you have a valve that is open when the spark occurs. Stuck valve or timing is off!