Have an MTD Yardman 42" deck riding mower powered by a 17.5 B&S engine. Mower often would not start last year. Went through a partial stroke and then hung up. Had a repair man look at it and he got it started, but wasn't sure what the problem had been. This year it started out fine but old problem returned. I replaced the starter switch and problem went away for a few weeks, but now it is back. Engine usually hangs up at about the point of max compression. Always at the same point. I can manually rotate through a full cycle, and I tried using a jump starter which gave me a full rotation, but then hung up at the same place. I also tried holding the key in the start position and got the engine to slowly rotate through one stroke. I also heard an electrical sizzling sound when I did it. Can someone help me? thanks.

I have a Craftsman walk behind with a 5.0 hp Tecumseh engine. It runs, but horribly. Spits gas out air intake. I have had the carb off, soaked in cleaner & rebuilt. The carb has been off & on at least 5 times. I don't think the carb could get any cleaner. Engine model # 143.975012