Either that, or an exhaust valve is stuck open; I've seen both. I burned down an old Snapper that had a stuck valve so be careful.
R&R the needle and seat in the float bowl, make sure your float is not holed (will be heavy and slosh with gas if it is). Drain the crankcase and refill with fresh oil before you start it; if it was the float stuck then enough gas can seep past the rings to fill the crankcase and hydraulically lock the engine when you start it next, wreaking much havoc.
If you have little or no compression when you turn it over to start it, the valve is stuck. Try the needle, seat, and float R&R first since that is easy and cheap to do.
Good luck with it.
Pete