Diesel Bombers - '10 Duramax Fuel Issue

I am in the military and we have a newer maintenance truck, '10 Silverado 6.6 Duramax, with 10k miles on it that is having a starting issue. The truck is bone stock and cranks good and strong, just replaced the fuel/water separator and fuel squirts out when the bleeder screw on the filter housing is opened. Also, the O-rings on the F/W separator are seated and the WIF sensor appears to be in good shape as well as the fuel head. The truck was on its way back from the field when it died out so I don't believe the notorious WIF sensor crack happened randomly while driving.

We have not discovered any leaks anywhere in the system, however it will only start after we pump up the primer until it is firm and only idles for a second before dying, but that pressure will leak down if left for a few minutes. We do not have the equipment to perform tests other than a dinky scan tool to check for DTCs. I would prefer to not tear down the top half of the motor to get down to the injection pump if we don't have to. Any parts that need to be replaced will have to be approved through the command's supply department before being able to be purchased from the stealership. This process can take a couple weeks so just throwing parts at the truck that are not the problem can easily turn into months before the truck is running again. This is our only field service truck so the sooner we can get it up and running, the better. We do have an '08 that is currently down due to Chevy's recent airbag recall and linkages for the driver door handles but otherwise runs fine, is there anything on that truck that we might be able to use to diagnose the issue? Any insight that anyone can provide would be greatly appreciated.