I had similar problems on my 2000 Chevy C2500 this week, The fuel pump would not come on. It was running when I dropped it off at a car wash/ oil change place. I ask them to change the oil and fuel filter. I left to go to the dentist next door to get a root canal. When I returned, they stated they changed the fuel filter and oil and now the truck won't start. The pump would not even come on.
I checked the truck and could not found anything that was obviously bad such as fuel pump relay or bad ground to pump. I then had the truck towed to my house. My wife worked for a car dealership (not Chevy but a competitor). One of their mechanics does sideline work. He lifted my bed out of the way and we jumped the fuel pump out by running a wire directly to the battery. Fuel pump did not respond changed the pump out. Pump now kicks on when you turn the key but truck would not start.
He then looked at the crankshaft sensor. While he was checking it, we kept turning the key on and off without starting the vehicle. The sensor was good. He then located the problem in the ignition switch. Going to get the part tomorrow.
Sarge