Fuel gauge not working

[WV Hillbilly]

1985 Ranger , 2.8 V6 , mechanical fuel pump so pump isn't in tank . Two wires connected to tank . Fuel gauge stays on empty all the time . How to troubleshoot before disassembling anything . Thanks in advance .

Update - I found the wire that goes from the sending unit in the tank to the fuel gauge was broken in the harness that runs toward the front of the truck . Break was about under the drivers door . Repaired break & gauge now works . I used an ohm meter & started at the tank & followed the wire until I didn't get a reading to isolate the break . Had to skin a little insulation off the wire as I went . Taped all skinned places after I found the break .

 

[rookieshooter]

Sounds like the gauge is not reading the Ohms or resistance in the sending unit in tank.
If you can get a reading on the two wires it might tell you something.
If you can find out how many Ohms you should have when on empty vs. how many Ohms there should be when filled.
Lets say you know the tank is full or at least half full and you are getting a reading that says empty then it may just be the sending unit in tank.
As the float in the tank goes up or down, so does the reading.
There is a series of wire windings that the float comes in contact with as it goes up or down. Those windings are known to break.

As an example 70 Ohms could be empty and 0 Ohms is full or vica versa.