I removed instrument cluster from my 1966 F100 Custom Cab in order to replace bezel and lens. Fuel gauge worked before removing but now does not work after reinstalling cluster. I grounded the orange wire going to the sending unit/ float assembly and gauge did not move. I removed instrument cluster voltage regulator, gave it a little shake and could hear something rattle inside it. I ordered a new regulator from Dennis Carpenter and installed. Gauge still not working. I have previously replaced sending unit/float assembly. I grounded the terminal for the orange wire on the back of the gauge, gauge did not move. What kind of reading should I be getting on the orange wire at the fuel tank sending unit/float assembly? Are there any other tests to try before ordering a new gauge? Thanks.
Edit: With test light I have power on 1 side of regulator, gets hot to the touch. At orange wire to the sending unit test light will not light up. Ohms tested sending unit. With out touching sending unit, meter reads OL. When touching sending unit meter reads 0.0. The Dennis Carpenter regulator has female terminal on the left, male on the right. Original regulator was opposite, female on right. male on left. Would that make a difference?

 

If you have an adjustable DC power supply, you could remove the gauge and bench test it from 0 to 5 volts DC input. Don't apply more than 5 volts maximum.

 

Do not have one of those. Thanks.

 

Here is an old thread to read it might help you figure out the problem. Fuel gauge issue - Ford Truck Enthusiasts Forums

 

Just the way they put it together. The female should read 12 volts with the key on where it plugs onto the male coming into the ICVR, the female connector should then read 5 volts where it leaves and goes to the gauge.

 

Thanks for the thread. Good read.

 

Thank you. I have 12 volts on the female wire to male post on ICVR. I have .5 volts on the male wire / female post of ICVR. I have .5 volts going into fuel gauge and .5 volts coming out of fuel gauge. I did continuity test across fuel gauge posts with wires disconnected, orange wire from gauge to sending unit and across ICVR with wires connected. All sounded a tone for continuity. No tone across ICVR with wires disconnected.

 

I believe I was able to get the fuel gauge working. I replaced the green-black "Y"- wire that connects the fuel gauge and temp gauge to the the ICVR. Even though that wire tested good for continuity, it would not give 5volts at the gauges. Seems to be working now.