hard start

ok I have been working on this truck for 3 months now..1997 ford f 250 7.3 powerstroke...If you can get it running it runs fine. replaced hpop, cam sensor. hooked up fuel pressure tester and it builds up pressure but when you shut it down it drops to zero...i don't mean gradually it goes from 80 to zero in less then 10 seconds. I have been chasing a fuel leak of and on but when I actually go to fin it i can't...but for that big of a leak it isn't on the engine.. could this be a leaking injector

ok I have been working on this truck for 3 months now..1997 ford f 250 7.3 powerstroke...If you can get it running it runs fine. replaced hpop, cam sensor. hooked up fuel pressure tester and it builds up pressure but when you shut it down it drops to zero...i don't mean gradually it goes from 80 to zero in less then 10 seconds. I have been chasing a fuel leak of and on but when I actually go to fin it i can't...but for that big of a leak it isn't on the engine.. could this be a leaking injector

Kind of late entry, but have you checked the o-rings on the injectors? I know that the 7.3's are notorious for bad o-rings on the injectors, and it will spew blue smoke for a little while on startup.