2000 S10 4.3L Fuel pump stopped working out of the blue. We Put a new Fuel Pump in, new harnes to fuel pump, new fuel filter, new relay, new fuses in IGN C and ECM B fuses. Still the pump will not turn on. We traced the wires and found that the gray wire to the pump is not getting power. Float on pump is working but not the pump itself. We traced it to the fuse box under the hood and tested it the and still no power. Double checked the fuses, Can feel the Relay clicking when key is turned on. Please Help. Ran out of Ideas of what to do. Name is Jon.

Did you verify that the relay terminals have the appropriate signals to them? 

ECM fuse B (20-amp) should provide power at all times to the orange wire of the fuel pump relay. The relay coil receives ground via the black wire, and relay coil gets power from the dark green/white wire. When the relay is closed, you should have battery power on the gray wire. 

The relay trigger wire should have power from the dark green/white wire in terminal 1 of the Vehicle Control Module (VCM) connector for the first couple of seconds after they key is turned to run (to prime the system) and when the truck is running. Checking for all the appropriate signals at the relay is where I would start. That is after I checked for diagnostic codes.

Believe the fuel relay is the middle relay out of the three in the left rear of the glove box. Last thing is to hot wire the fuel pump if you can not get it scanned, see if the pump is bad unless your going to have a shop work on changing the fuel pump.
Good luck and hope this helps. keep me posted.