Was mowing with the craftsman tractor mower, finally got it working again. It had needed a new battery. Anyway, it worked fine for a bit, no real problems. I hit a particularly thick patch of grass on an uphill, and the engine backfired a few times then began belching thick white smoke. Thick enough that I could not see my hand in front of me... I don't want to think about what it did to my lungs. I let the machine sit overnight, then tried it again in the morning. It runs clean when its on flat, smooth ground, but smokes if the ride is bumpy, or if you get on any kind of a slope. It also smokes if you hit any thick grass with the mower engaged. Our current working theory is that water somehow got in the gas, but we're open to any suggestions.

Thanks in advance,
Mike