I will second the stuck needle valve theory. My cub would not start this spring. I worked on it for 3 days. I finally pushed it up on the trailer and hauled it tem miles north on the roughest road in Coshocton County. I pushed it off the trailer where the shop owner wanted it. Two days later he called and said it was ready. I went up, loaded it on the trailer and went in to find out what I owed him. He said no charge, I asked what the problem was and he said when they went out to get it it started on the first try and they could not get it to not start. He said he had another one do the same thing two years in a row, and the only thing they could figure is the needle valve sticks. If mine does it again I am going to load it up and take it for a ride on a rough road. If you have a trailer and a rough stretch of road it would be worth a try,