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?