Cummins N14 Long Crank Tried the Norm

I have a N14 Celect+ it takes about 15secs cranking to start once going runs perfect, we have changed the ECU cooler plate, installed 2 back flow restrictors one at pump one at tank, new fuel shut off. Nothing has changed the long crank, No codes in ECM, ECM was replaced for a unrelated issue but it didn't change the long crank. any Help would be greatly appreciated

 

While cranking, While Running, Or static when off, We haven't checked pressure... didn't go that route because once running shes a work horse runs great, the long crank has only become a real issue because its winter , so in that fact the pump is working fine, we were under the impression that its bleeding down that's why we went the route we did

 

I think hes talking about the one in the cooler plate, and we have replaced the compete cooler plate so I don't think that's the issue the fuel line from the pump goes to a hard line the enters the rear of the head

 

Just Pulled filter/screen out of fuel pump (top of pump toward mounting flange under big flat head screw) perfect condition no metal no build up cleaned installed still long crank...ahhhhh

 

also In my case we have check valves at pump, at cooler and at tank pick up.. the tank one was my idea normally everyone has one at pump and in cooler plate.. but still long crank and no different than without any of the added check valves.. just a note