Z71 will not start

[Bigjanskier]

Can someone PLEASE HELP!!!
I have a 2005 Z71 that will not start. It has gas, fuel pressure, spark, signal to fuel injectors, new fuel pump, fuel injectors, rails, lines... It sort of starts for a second and stops. It is NOT the passcode/security as no lights are on. The check engine light is on. I get a signal from odb reader that says communication link failure so i cant get any codes.
It seems like it wants to start but maybe the computer is getting a signal to shut it down. I think its a sensor but really have no idea. Can anyone solve this mystery for me?

 

[Mitzee]

I am having a similar issue with my new 2016 z71, been to dealer 3 times and they can't figure it out. They know there is an issue but don't know what to do. It try's to start but I have to pump gas to get it to start

Very frustrating