Fuel gauge weirdness

[east high]

My fuel gauge has never worked properly. It pegs when I turn the key and stays pegged until the tank gets below half tank when it starts to pogo between full and empty. After that it'll stay on empty. It even happens when the sender is disconnected. :confused:

I tested the sender (it's new) and it's working properly, so I'm guessing it's a grounding issue or something. The top of the sender has a 'W' and a 'T' at each terminal, and the gauge has a 'B' and a 'T'. Does anyone know what these mean and if they're related in any way?

[scott]

if the sending unit has two terminals i'd guess that one i for a low fuel warning light the other for the gauge. power runs to the gauge from the fuse that is hot when ignition is on the ground runs from the gauge to the ending unit. the sending unit will interupt the ground when tank is full when the tank is empty the ground is complete and in between there is a degree of continuity in the groung. the warning light doesn't have a degree of gound, it's either grounded or not. grounded when the tank reaches a certain level and the light goes on.

maybe you have the gauge ground going to the warning light terminal. my guess (again) is that the B on the gauge goes to power (B for Battery) and the T to the tank. The W on the sender might be for Warning Light. Can't remember exactly how i hooked mine up and i'm sorry the truck and i are a bit apart right now or i'd go check for you

[SafeAirOne]

I think all the senders (except diesels and V8s) have 2 terminals--At least my SIII 109 does. Mine is the type that has a cam ring that holds it to the tank (not screws).

The terminal that is insulated is the positive one and the one that is attached to the metal top part of the sender is the ground.

My gas guage was screwy for a while too--It would read 1/2 tank when it was full and go down in a random manner as fuel was used.

It took me a while to figure out that the wires were swithced on the fuel sender. The positive wire was on the ground terminal and the ground was attached to the insulated positive terminal.

When I swapped them around the guage read properly.