its an 04 lb7 duramax. to start, heres a list of what all has been replaced...
-fuel filter housing
-cp3
-suction side fuel lines
-injectors
-injector supply tubes
-FRP sensor

currently getting 2 mpa at crank (fluctuated between 1 and 2). can hand prime at housing up to 10 psi (using test port beside alternator). have pumped until hard and bled at that test fitting as well until no air came out. when pumped up to 10 psi, slowly bleeds down to zero over the course of about 2 minutes. when cranking, ticks down to zero in about 15 seconds. no codes when scanned either

any ideas on where to look for an issue here?

 

unplug the FPR on the back of the CP3 and see what you get, its a real pain in the butt using long angled needle nose pliers will help.

you're having a leakdown issue somewhere