Roxywheels said:If it works when you wiggle the fuse at it's connector then you probably have a bad connection there. Pull the fuse block and check the pins at that fuse. They may be loose or corroded. It's most likely a simple fix.
If that doesn't solve your problem, unhook the fuel gauge sending unit from it's wire harness at the tank. Verify proper voltages with a DMM. If the power wire checks out OK another wire or the sending unit itself may be at fault. If the other wires check out OK pull the sending unit and bench test it. The FSM for your truck should give you all the necessary specs you need.