Fuel issue on Silverado

2005 Silverado. I cannot get it to turn over. It cranks but
does not turn on. I checked to see if I could hear the pump
in the tank prime and i got no sound.......so i lowered the
tank, and checked the pump itself by applying voltage to it
and it worked.......put a gauge on it and reading close to 50
psi. So am thinking that is working great on that end. I
decided to check for voltage at the tank connection and
see that there is no voltage going to the back. I checked at
the relay box and see that there is voltage there, and feel
that the relay is clicking so am at a standstill now with this.
Is there a cut off witch somewhere on these vehicles that
wont allow power to go to the fuel pump? I did run a
straight wire from the battery via a switch to the pump and
its getting fuel coming into the rail at around 45 psi but not
cranking on........could it be a sensor? Or cut off switch?