It can take a while.

Be sure that the electric lift pump is working-the oil pressure switch send power to it when oil pressure is high enough.

Thanks that was the problem it was plugged in but it wasn't making contact .The little black box on the side of the pump is that the positive possession sensor

The black box on the side of the electronic IP is the FSD/PMD.
fuel solenoid driver
pump mounted driver

The black box on the side of a mechanical IP is the TPS-throttle position sensor.

Thanks I just replaced my IP mechanical and now when I am driving the truck seems to go fast by it's self and or slow down like it looses power,then pick up power. It also jerks like the tps is cutting in and out . Can the tps be my problem.

I would look more into air getting into the fuel.
replace the IP fuel return line with clear diesel rated fuel line and with the engine idling safely-watch for bubbles.
Bubbles indicate air is getting into the fuel supply.

The TPS should only be an input for the trans computer.

Great write-up on installation of a replacement IP. Question I have is how does one install the DB2 injection pump so that it is in the right order for fuel delivery. Is it possible to have it 180 degrees out - still with pin in the slotted hole? My son put a new IP on his 1991 GM 6.2 but said he rotated the crank after he had IP off because he could not get holes to line up. Therefore if he rotated the lower crank 360 how does the IP pump know where it starts off? He has it all back together, has bleed fuel lines, filter, etc. Installed new fuel filter, and glow plugs. Also looked at return fuel line while pumping and there does not appear to be any air in the fuel. Truck just will not start. New IP was put on with the exact same place on timing line. Which happens to be basically the factory scribed line.

By the way the IP pump was originally changed because the diesel engine ran away on my son. He said it was crazy. He stopped it by stuffing a jacket into the intake. He got lucky and stopped it quickly. Local GM shop quoted us approx 3000 to fix and said IP pump was problem. SO we bought a rebuilt one and changed it ourselves.

Sorry for the dumb questions. I am new to working on diesels and my son is also just learning. Thank you in advance for any help you can provide.

Yes he likely has the IP 180 degrees out since the IP turns at 1/2 the speed of the crankshaft.

He would have been better off turning the IP drive flange to line up the holes.

He most likely needs to remove the balamcer,waterpump and timing cover to line up the timing marks properly now and maybey even inspect the timing chain while there,also inspect the balancer and drive pulley for deterioration and replace the timing cover oil seal and perhaps even the waterpump?

Google 6.5 diesel military manual,join the forum that has it online and download it for free for the detailed pictures and instructions.