I've been messing with the motor, new glow plug, new fuel filter, factory carb settings. The problem I'm having is that the damn thing won't suck fuel when I try to start it. I've tried taking the line off before the fuel filter and just turning the motor over to see if fuel comes out, but it doesn't. When I blow into the exhaust end, fuel will go right to the carb. But when I turn it the motor over, the fuel goes BACKWARDS and back into the tank. What gives?