I have a 1995 F150 5.0V8 that the fuel gauge doesn't work properly. When completely full it registers 1/4 tank. It has had a new tank and fuel pump installed by the previous owner and the wiring has been spliced into the new plug that plugs into the jumper from the fuel pump. I have been looking for a wiring diagram to double check the wiring, but have been unable to find it thus far. Can I test the guage to eliminate that possiblity?