I have a 1991 Ford F-350 dually with a 7.3L IDI naturally aspirated diesel, and 481,536 miles. I have gone through the fuel system, sealing up fuel leaks, and replacing injectors, because when I first bought this truck, the engine fired up really fast, like in 3 cranks. Now and just before I went through the fuel system, it will fire up quick, and die, then take a long time to fire again, as if I'm having to re prime the fuel system every time. Now, if the truck only sits for about 1 or 2 hours, it's fine, but if it sits for longer, such as a full shift at work, it'll have this issue. Need advise as to where to look now, as I'm out of ideas as to what could be allowing the fuel system to lose it's prime.