I ran out of gas a few times in a short period, before finding out that the cars tank was dented right where the float was, so it would never show empty.

After I replaced the tank I never wanted to run out of gas again, so decided to put some type of warning system for low fuel like some cars have. Ford had a system on newer cars that was plugged into the dash circuit board. But my sender wouldn't work with that one.

Different senders have different resistances when full and empty. They must be matched to the gauge. Here is a list of a few.

OHMS Full / Empty	CAR Make
0 - 90 ohms	GM 1965 and up
73 - 10 ohms	Fords before 87 & most Chryslers
16 - 158 ohms	Fords 1987 and newer
0 - 30 ohms	GM older than 1965
240 - 33.5 ohms	Standard on many cars

There were a few homemade circuits on the Web that would have worked, such as www.westol.com/~beaurega/gas.htm, but I feel factory stuff usually is more dependable. This circuit should work with any car that uses about the same ohms as the 87 and older.

On cars before 87 Ford put a Fuel module that was plugged into the harness.

No doubt about what that thing is anyway.

It has to be the most clearly marked component ever made.

On Mustangs it is above the glovebox, and on LTDs it is above the gas pedal.

The hole in the front was drilled by me to fine tune the response, but I never used it.

Here is the insides of the circuit board. 1970's technology at its' best.

Here is the wiring plug from the front.

1: This is 12V out to the light. On some cars it was a bulb, and others a LED circuit. I used a resistor and an led.

2: 12Volts in from the key.

3: Ground.

4: This has to hook up to the circuit board. It has been a year since I did this, but I think it hooked to the 5V circuit that went to the gauges.

5: Spliced into the fuel sender from the tank.

This is the back of the Instrument panel circuit board.

On mine, I needed to add a jumper wire to tie into the gauge circuit. Now it was all wired into the factory plug for easy of service. I soldered a wire to the circuit board lead used by the ammeter.

You can also see that the warning lights on the right were rewired into a plug from a probe, also for ease of removal.

I also changed the Ammeter to a Voltmeter. One from a S-10 minitruck bolted right in, although I painted the red parts of the face green to match. 12 Volts is 12 volts.

Here is the wire and led sneaking up to the fuel gauge. A little hole was drilled and it was glued in place. An inline resistor was used to drop the signal to the led level. [don't remember what size it was]

I drained the tank and the light came on, then slowly filled it again. It went out right at 2 gallons. Good enough.

This was a nice little project. The hard part was figuring out the wiring. The light is a nice reassurance, and sometimes a nagging reminder, of the fuel left.