I have a John Deere LX172 with a single cylinder 14hp Kawasaki engine (FC420V). It wont start. If you crank it long enough it will pop a little then backfire. I have drained and cleaned the fuel tank and line, cleaned the carburetor bowl, replaced the igniter (small electrical part on the side), replaced the fuel filter, both air filters and the spark plug. I checked the spark and it is good. The fuel pump works. The engine was running great when I put it away several weeks ago. I was using sta-bil in the gas for the last 2 months or so. however, the igniter went out on it about a month ago. The symptoms were the same. It has compression of about 110-120. The tester is old so I don't know how accurate it is. This engine is 10 years old so and this is the first time it won't start (other than the igniter). Maintenance has been performed regularly. Any suggestions?