It's the Ethanol. I never had a problem with old gas until gas started to be mixed with large quantities of Ethanol. Last year I had problems with my tiller, chainsaw and my stovebolt after they had sat awhile. The tiller and the Stovebolt I fixed by running them hard through a couple of tanks of gas. The chainsaw went in for service. Interestingly enough, the chainsaw place sold pure gas with no alcohol in quart cans because this problem is so common. A quart sold for about $4.50.
Kurt
