I was driving down the road one day and it just died out on me and would not restart. We just put a tune up on it and changed the fuel pump and it was working just fine but when you try to start it it just turns over and backfires and floods itself please help me to figure this out we think it could be the timing chain or could it be something else? We would like to know before we start taking it apart how will we know for sure? PLEASE HELP!!!!!