sorry going to be long post.2001 cummins quad adr. dap 150s fass 150. installed injectors and quad about 6 months ago,everything fine until last week, towed 10000 lb trailer 100 mi fine, 100 mi back home fine, next morning no start o fuelpressure, loosened fuel filter primed fass started fine, next time to start same. i checked for leaks found none, bolt on back of head ,t back of head,all fuel lines same no start 0 fuel pressure until i prime fass. removed fuel and water sep checked gaskets installed now have instant fuel pressure on key bump and 25 sec starter bump,still have a long crank after truck sits for a while. park nose down starts fine.question can injector or injector tube be cause and still have instant fuel pressure?

Check the suction line which will never leak out but suck air in. The only way to find these leaks is to pressurized the fuel tank after you have a good prime. Then you might see moist spots where it was dry.