Before putting the mower in the garage after mowing the yard, I shut it off for approx 10 min while using the leaf blower. When I tried to start, it never cranked but had been running fine when I cut the front and back. I even stopped and started it several times while I had to get off the mower and move stuff around. Checking the normal things, it still wouldn't start:
battery - ok
Gas - clean and flowing
Oil - full, clean, changed two weeks ago
Air filter - clean
Gas filter - clean, flowing
Carb - clean, parts moving freely
Spark - cleaned, the ensured it was sparking
Electrical connections - checked out ok
Flywheel/coil - removed dirt and very light rust
Pushed it into the garage and let it sit for a few hours, then tried again with the air filter off it backfires with the choke engaged through the air intake and muffler. It is getting gas, but never sounds like it is actually trying to run.
Last edited by inetquestion; 04-14-2010 at 08:50 PM.
Took the head off to find the upper valve seat had come out. Tapped it back in with a punch and also around the rim to tighten the fit. Cranked on the first try and runs perfect. Hoping it doesn't happen again...