I have a new OS 40fp engine {I know the Os don't make 40fp anymore but this one was never run and was still in the box.} I have ran the engine on a test stand 2 tanks of fuel then i put it on the airplane. the engine starts fine and runs great for about 4 to 5 minutes then it quits. now yesterday it quit at a vary bad time and I crashed the plane .I have about 4 8oz tanks of fuel ran in it with the engine installed on the plane. I have changed the glow plug 3 times we have worked with the idle and high speed set screwsand still can't keep the engine running. I been working with some of the guy at the club field and no one can help me out can someone here tell what the problem could be. Please help.