Hello this is my first diesel so bare with me here. I bought a 99 crew cab 4 wheel drive that has been rolled over. I have only gotten it to start with starting fluid but it won't stay running. The glow plug relay was bad so I replaced it. Still won't start. Unplugged ICP. Last night I hooked a gauge to the top fitting on the back of the fuel bowl and got 60 psi when the pump spooled up. As soon as the pump shuts off the pressure drops to 15 or so. Is this normal? While cranking the pressure fluctuates from 35 to 60. HPOP level is good. The only codes it has shown so far are 1280, 0237, 0603, and 0470. I would appreciate any help y'all can give.