there are ways to check the voltage coming from the sending unit in the tank. Its usually one of three things:
1: bad sending unit in tank (maybe attached to fuel pump)
2: Bad Wire somewhere between the sending unit and guage.
3: Bad Fuel Guage.
Easiest way is to get a repair manual and run through the checks.
1996 Ranger XLT V6 4.0 5 Speed Manual.