rail valve? are you talking about the brass valve left of the alternator? if so that is on the suction side if the CP3 and you wont get fuel while cranking unless you have a lift pump. if not enlighten me, i am confused
by the way, ecm needs to see at least 10 Mpa (1450 PSI) for it to fire the injectors. with a scanner check the actual fuel PSI while cranking
try priming till hard, cranking, priming till hard, cranking, priming till hard, etc. do this several times. if it fires then you may be lucky and just had air in the lines. and it may be a simple fix.
if not i may be a CP3 or injectors