make sure that you aren't flooding the engine when you prime it, it only takes me one or two rotations of the crank to prime the fuel to the carb, if you continue to prime after the fuel has traveled to the carb then you will flood the motor. I just rebuilt my motor and The first time I went to run it and break it in the truck started on the second pull, it is all about priming it the fuel just to the opening of the carb.