More fuel gauge problems

[vince1]

My Equus 90 ohm fuel gauge only worked for a short time with the Jeep Cj5 fuel tank that is mounted between the frame rails. Then it would do lots of flickering and other weird stuff. A few years ago I had swapped out the 250 in the 66 C10 and put in a 350 from a 79 P/U. Today I finally added some more grounds from engine to frame to body and fuel tank to frame.

Tank is about 1/3 full and the gauge now pegs past full. I have a TPI 120 basic meter with only one ohm setting which is good for 2k ohms. The reading I get from the sending unit wire with it removed from the gauge is .022 and the meter makes the noise. My question is, what is the significance of the .022 reading on the meter? Is it .022 ohms or is it 22 ohms? Thanks.

[RustyPile]

I'm not familiar with TPI test meters so I can't tell you if "external calculations" are needed to determine the reading. It's possible the "noise" is an alarm that means the reading you're trying to take is out of limits of the meter's capability.

Flickering and erratic fuel readings could mean loose connections. Fuel gauge pegged over full indicates an open circuit between the gauge and the sending unit resistor. Disconnect the wire at the sending unit and ground it. If the gauge moves to the empty position, this indicates the gauge is working and the related wiring circuits are in good condition. if it stays "over full", there is an open in the wire and the gauge. Could be a loose plug connection, could be a break in the wire.

I suggest you use a meter you know how to operate for the following tests. Remove the fuel sending unit and check the resistance.. Connect one lead of the meter to the housing. Connect the other lead to the wire terminal. Move the float through its range of travel.. At the "empty" position, you should read at or very near zero ohms. At the full position, you should read at or near 90 ohms. Half way of its travel, you should read approximately 45 ohms. Any variations means the sending unit is bad.