If you're saying it only has 100 psi rail pressure, then yes, that's far too low to start. The injection pump is the most likely culprit, but an injector sticking open can make low pressure as well. If it is an injector problem, you'll have white smoke while cranking. The CP4 injection pumps on these like to fail spectacularly when they go, so you'll want to pull the pressure regulator and maybe some injector lines for good measure, and look for metal shavings. If you find any, you need the entire high pressure fuel system, and a thorough flush of the lines and tank.

James Kuhns
Owner/Technician
Auto Tech Solutions
Chatham, New York, USA