My Lawn Boy MTD mower worked last week and now will not start.
1. Check spark plug, have spark when handle is pulled
2. Replace fuel with fresh, drained carb bowl
3. Checked air filter, looks good. Removed and tried no change
4. Oil is good
Engine turns over and it sounds like it is back firing. Could the exhaust vaule be stuck open?
Ran great last week, cleaned and washed with water. Put away in shed.

Could be a valve problem, check the flywheel key though if you are backfiring. And mtd to my knowledge does not manufacture lawn boy, not aware of this any how.