Have you traced the wiring from the fuel pump all the way back to the fuse block to verify it's intact and not receiving power at the fuse block?

 

Perhaps corrosion in the underhood fuse box.

If not trace the wire. Its a slightly thicker grey wire on my '05 with a 5.3

 

I just had the same problem happened to my 2011. I went through everything that you did. Replaced the fuel pump, replaced Chevy's crappy idea of a ground strap. And did checks all the way through the system. What it ended up being was a loose fuse block in the engine compartment. I tightened down the holding bolts and now it runs like a champl

 

That's the second time iv read that on these vans in 2 days.

Al

 

Ok so I abandoned all hope for a while and now I’m back at it but now it makes even less sense! So I tested my voltage at the pump connector and I’m getting full 12v for 2 seconds when I turn the key on and then it drops to about 5 volts then when I crank it over it jumps up to 12v again. Seems like how it’s supposed to work right... well nope pump don’t do nothin, but when I hot wire the pump it springs to life. So check off pump for being a problem and check off power to the pump as a problem, what’s left? The connector. I replaced it with my own where I can physically see the wires touching the terminals and also test that the power from the battery is entering the connector at the pump. Sooo is my meter lying to me? Every single thing checks out. But my pump sits there dead. I started following the gray power wire back to the fuse block to see if it might be worn out or doing something it should be but I discovered it doesn’t simply go back to the fuse block. Instead it gets packed up and taped together with 100 other wires and shoved between the intake and the top of the fire wall before going back under the van. So I guess my next question is just how bad would it be to simply run a fused wire from my battery into my cab with a switch that then runs to my pump? Is it going to be horrible on gas cuz the ecm isn’t controlling it? Something insane is going on with this fuel circuit and I want to simplify it.

 

Jim, it's a simple circuit, let's get it fixed

You have 2 circuits, the primary that operates the relay and the secondary that operates the pump.

First job is to determine which circuit is at fault.

Find the pump relay,
Get a 2nd set of hands,
You place 2 fingers on the relay,
Get your buddy to turn on the key (don't try to start),
If the primary circuit is good, you will feel the relay click,
If the relay does not click, the problem could be wiring, dirty/loose/blown fuse, bad fuse panel, bad ignition switch and as you suggested the PCM

If the relay operates, look at pump wiring and pump grounds.

Note, a meter reads voltage without a load (no current draw), the pump is a big load and will draw current, this will change the voltage readings if you have dirty connections, including a dirty ground connection.

 

The relay clicks and I have already replace the ground and pump connector

 

Pull out the relay. Put your meter lead to relay socket terminal 30 and the other to ground. There shd be 12V.
Put a jumper wire in the socket side female terminals 30 and 87. Fuel pump shd get a direct 12V and energize the pump. Report back your result.

 

Yep, my suggestion as well.

Jim, you can still have bad/dirty grounds and power connections. Replacing the tank to frame ground does not prove the ground back to the battery is good.
Also, new connectors, does not prove the power through the wires, the fuse panel, the fuse and to the battery are clean and good.

If after @bazar01 's relay strap is tried and it doesn't work, the next step is to read the voltage across the pump terminals. If there is a voltage drop, this will tell us where to look for the bad connection

 

If there is 12V at terminal 30 in the relay socket and the jumper on terminals 30 and 87 did not energize the pump, the 12V feed from terminal 87 of the relay socket to pump terminal is suspect and the wire feed needs to be tested for continuity.

 

I have 12v at 30 but when I jump the terminals I get nothing, however with the terminals jumped I am reading 12v at the pump connector but it’s not powering the pump, I’m assuming this has to do with a lousy ground but I’m having trouble finding info on where exactly all the ground straps are located on this van

 

Temp ground test.
Run a wire from battery neg to the pump ground, if pump starts, the frame etc is missing a ground

 

Bingo. Found a ground strap on the front frame rail that looked like it was part of the titanic. Ran a thick wire from the frame to the negative battery terminal and turned they key and the pump pissed gas all over the side of my van. You are all saints and scholars thank you.