no fuel to injectors

Yes it's a grounding issue. If you have voltage at wires, and pump operates when direct voltage is applied, then check the entire circuit on the ground side until you find a break/corrosion/looseness.

what is the best way to check the entire circuit??

I was trying to locate a diagram for you but was unable to at the moment. There is a chassis ground for your pump, but I'm not exactly sure as I can't remember every vehicle. But you should be able to follow the wires leading to/from the pump. Probe them with a test light/volt meter and make sure there's no looseness/corrosion at the wires/connectors.

Hopefully another tech on 2carpros will be able to locate a diagram for you as it would be easier to see than tell.

I was able to locate a diagram from auto zone, my question is: if there is a loose / corroded wire somewhere, why would I still get 12v at the pump plug?? which I do every time I check it.

There's a positive side and a negative side. If you connect a volt meter to the positive side, you're reading voltage from the relay to the pump. The voltmeter is providing the ground for the circuit, not the pump. You need to find the ground circuit and test it for continuity and high resistance.

that makes sense. here's another thing that I tried to se if it would fire up. since the pump works on external power, we had it hooked up and you can hear it pumping nice and tried to fire the motor but i wouldn't?? should it have? also, is it connected in any way to the 4*4 system?

No to both. The computer controls the pump and if it doesn't see the pump operating through it's own circuit it won't fire the injectors

I read your previous answer again about testing with the volt meter. just to clarify something. I tested the plug inserting both ends - red and black- testers of the volt meter inside the plug holes for the ground, black and pink with black strip,. another ward i did not use any outside ground sorce.

That plug also contains the circuit for the fuel gauge on your dash.

should i then test all the plug ports along with the black ground insert or should i go ahead and fish the bad ground somewhere??

I can't say with certainty that will be your problem, but from what you've done so far, it sounds like that would be your issue. (Since you previously stated you had fuel pressure while powering the pump externally, I assume you have no blockage in line and spray at injectors because that is the normal place to check that you have fuel to engine)

If I'm correct and you've determined the rest of fuel system to be good, then your issue must be with the ground somewhere. But since I currently don't have access and can't locate a diagram of your specific truck, I can't tell you exactly where to check other than on the ground side of the circuit.

I just wanted to let you know that we found the issue with the truck and it was a wiring-grounding- issue in the circuit. thanks.
however after we got the truck running and good the light for the rear antibrake comes on after i drive 3-4 miles. i shook the wires and bled the brakesbut it still comes on after i turn the truck on and drive few miles???????????

You could check the wheel speed sensors and all the wiring/connectors for that circuit.