[jonfromhamilton]

does anyone have any information regarding the wiring of the stock sierra fuel gauge?
from what I can tell there are 4 points in the back of the gauge.
I have removed the tacho and temperature gauge from the cluster and that has obvioussly upset the continuity of the fuel gauge.
I have experimented running wires from point to point to try and short cut the poewr supplies or whatever the gauge needs but there are so many points it's hard to know which ones is earth, power supply, signal, just for fun.

anyone done anything with this before?
I guess I will just keep experimenting with different combinations.

[want33s]

As far as I know the gauge gets 12V+ from the cluster and the earth is at the sender.
Variable resistance to earth is what the gauge works on.

[whincup]

yes that would make sense since only one wire comes from the sender. IIRC it's a yellow wire

[christover1]

guage may have a light triggered by headlight or parker?

[Mickc]

Had look some time ago and from memory,
Fuel Guage
The earth ? is marked E on circuit.
The power is marked FU.

If you look at fuel gauge, the FU also feed's a bi-metal arm with coil
along the arm and set of contacts at end.

The output side is terminal marked 7V. ( 7volts ? never tested this)
The 7V circuit feed's temp guage. (and other things?)

The last wire marked E+ is part of ing and charge warning light circuit,
but it also connects to taco and fuel guage via a Diode.

[jonfromhamilton]

Awesome answers guys.
I have it operational now, there was continuity between the wire that goes to the fuel gauge at the tank end of the car which was Y/R and the Y/R wire in the plug in the dash, that went to the "FU" on the back of the cluster.
there are 3 bolts and one screw, the screw was earthed so I put 12v onto the terminal G+ on the back of the cluster and left one bear.
there are 2 resistors in the gauge, i only connected one so I don't know what the other one is fore, it has a switch connected to it so perhaps it is for a fuel light but it's not connected.
my fuel gauge now reads TOTALLY FULL which may be because the tank is quite full and I haven't bent the sender correctly (I made a new tank) but i have a 5 litre red, plastic, in-car reserve tank so I will just run the car out and hopefully I spot the needle dropping as this happens and all I need to do is bend the sender correctly.
I took a pic which I will try post up some time tonight.