Just bought this outboard,will not start ive checked the flywheel key, it was in two halfs i put a new 1 in and tried to start,but just backfires and sometimes runs for a few seconds,took the 3 carbs out and blew them out ,still will not run and backfires,im now wondering if its the coil but theres a great spark on all 3 plugs any help would be much appriciated 
