Imperial Home Page -> Repair -> Fuel -> 1981-1983 Tips -> Fuel Sender Resistance
Tip from Bob:
Fuel-Sender Information The following are the resistance readings for the In-Tank Fuel gage Sending Unit. These readings are from a new unit for applications after 6 April 1981 (most prior-built cars were dealer-corrected). There are two sets of resistance values, the first as measured at the float resistor terminals, the second at the terminals that are external to the tank - where the plug-in connectors are. There is innate resistance in the wires themselves. First set: Empty, lowest float at the arm Down stop: 149 ohms and Full, highest float at the arm Up stop: 18.5 ohms. Second set: Empty: 169 ohms and Full: 39 ohms. The best way to determine if the unit is fit for use is to connect it to the harness connectors and holding it in the vertical position, move the float arm from empty to full and have a helper verify the readings on the instrument cluster; half full should read 8 or 9 gallons.
Addition:
The difference between the two units is the value of the resistance band within the arc of travel in the housing. The amount of travel is the same, but the amount of resistance is different. Part number 4051674 is supposed to be available for the EFI Imperials. However, I have "adjusted" a conventional unit as follows: The float arm is forced into a hole inside the housing and can be gently repositioned in the hole, in either direction by moving it further at one end or the other of travel limit. Without removing the fuel tank, disconnect the wire leads from the existing level indicator and connect them to the new unit. With another person in the car with the dash illuminated, "on," position the float assy. in a vertical position and move the float up and down and get the dash reading from the other person. Adjust the float arm shaft in the hole in the housing as described above. Check the level at approximately the half-full mark by moving the float arm to half its travel - read 8 or 9 gallons on the dash readout. Try the extreme down position to get as close as possible to the empty and read again. Play with this until it's where it ought to be. The float only package part number 4051622 is for early '81 cars, build date up to 6 April 1981, after, use number 4051484.
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