Not sure what to do with this problem ? I could run my Husqvarna 51 till it would run out oh gas no problem. I would shut it off for like 5 minutes and it would not start put in a new plug and the saw would fire right up . I never had much trouble with this saw . What I did notice the temperature was 80 or more when I had this trouble . I did the same test today temperature around 60 no problem. Not thinking vapor lock don't hear sizzle and starts with new plug . Been running a NGK bpmr7a . I would like to try different heat range .