My dads 03 loses fuel prime if its below freezing, at first we thought the truck was gelling up but Its been below zero here for the past week every morning(except yesterday) and the truck will start then shut off within 10 sec. then if I prime it, it starts right up and runs fine. Saturday I went out to start it and primed it first (witch you could tell it needed by the way it primed) and it fired right up and ran fine. Is there a check valve I should take a look at? The problem is hit and miss if its above 15 degrees. Thanks.