defective fuel pump?

 Hello, I own a 2000 express 1500 conversion van 5.7 liter engine.
 
about 2 weeks ago I went shopping and when I got into my van to go home, I started my van and it ran for about 20 seconds then it shut off.  it would crank over but it would not start. the temperature on that day was about 20 degrees outside, I continued to try and start it until the battery died out. so I had it towed to my home.
 
I connected an actron code scanner to see if it had any trouble codes, but no codes.  Then I turned the ignition to see if I could hear the fuel pump, no sound whatsoever.  Then I checked the fuel pump relay and the fuel pump fuse.  They both checked out good.  Then I dropped the fuel tank and took out the fuel pump.  Then I bench tested it by running 12 volts through it-it functioned.  So I removed the electrical harness from the fuel tank and I connected it back onto the harness.  Then I opened the ignition and the fuel pump operated for about 2 seconds which is the required time to prime the fuel lines.  I put the fuel pump back into the tank and replaced the tank back into the van.  At this time, I was using a booster pack to start the van due to dead battery.  It started up fine.  I let it run for a few minutes to let the battery charge.  I shut down and attempted to start again but the battery was dead due to sitting outside in very cold weather.  So then I let the van sit for about 1 week until I could purchase a new battery.  I installed the new battery and when I tried to start it, the fuel pump did not work at all.  I have checked all the wiring and everything seems fine.  Do you think the fuel pump is shot?  Or could it be something else?  Any feedback would be greatly appreciated. 
 
Sincerely,
 
Strictly Chevy
    
 

Have a 2500 for my daily driver have 3500's  for work. The Gm fuel pumps are a bad design. I had mine just quit. We have located the location of the pumps on our vans so we just cut the floor and replace them. 

        Check 12V to computer. I've found the smaller red wire on the battery terminal will break and cause the computer not to power up. Follow the redwire. One visual thing you'll notice is the lights on the dash don't look totally correct when you turn on the ingnition key to the first click.

I have a 99 sounds like it may e having the exact same problem.  I noticed that when I try and connect a scan tool to pull codes, it only continues to say linking.  Would this be due to lack of power.  i also am not getting any power to fuse pump.  Suggestions?  Help.  This is my money maker.