I went today to try and start my mower up. I had taken the battery out be for I stored it. I put fuel stablizer in it also and ran it for about 20 min. This was the first time I have tried to start it in about 2 months. When I try and start it, it sounds like it wants to start but it just won't go. It back fired a couple of time also. What should I do to get it going?