Well, I'm scratching my head now. Subject is a Yard Machine 12.5 mower just over a year old. I recently moved (mower included) and the first time I used the mower since the move, after running for about 10 minutes, it died while I was hooking up the yard trailer (mower idling). It just shut off like it ran out of gas. It's been outside and uncovered for the first time, so I drained the gas and carb bowl to see if water was there. None. Also checked the spark plug. It wasn't fouled, but I changed it anyway. Still wouldn't start. So I gave it a break (me) and tried again today. It fired up today, but continuously backfired through the carb while running, so I pulled the crank bolt and checked the alignment key and it's perfect, so I'm at a loss. I can feel the compression and exhaust strokes when turning the engine by hand, so?? Not sure what else to do, but the lawn is going to outgrow the house if I don't fix it soon!

Check your valves?