1968 Ford Fairlane V8 Two Wheel Drive Automatic lots miles
Our tank read 1/2 when full. We installed a NOS sending unit from classic car auto parts with the same result. We found and installed a OEM fuel gauge (new in the box) and still have the same problem. I can not find any factory resistance readings to go buy. The sending unit has no ground wire, the tank is screwed into the car (bottom of trunk) thus it should be grounded.
I tried a sunpro gauge, but I found out you have to have a " married set" to work right, and the oem sending unit has the fuel line running throught it where as sunpro's does not.
With the ignition switch turned to the on position the voltage feed wire Black with green stripe the voltage should oscillate between 0 and 10 volts. If it does not then the constant voltage regulator is defective. Does the temp guage work all right? If there is a fluciation in it then replace the regulator. The regulator is held on the back of the instrament panel on the right side. There are two wires that slide on. One is black with a green stripe and the other is black. When removing make sure you note the post each wire comes off so you know what wire goes to what side. The one towards the bottom will be the black wire The regulator is held on by a screw. Had same problem with my 66