Thanks Ron & Ola for the suggestions. I took apart another defective unit and I see what is most likely happening. The resistor winding's surface wears down with the tension of the slider. The defective one was polished smooth, hence no resistive differential as the float moves the shaft. It seems to be more polished near the bottom of the tank for whatever reason and that may explain my unit's erratic behavior as the tank empties. Since the removal of the sending unit's cover is a tricky procedure, I decided to leave the somewhat working unit alone. I did bend the float arm to get a more accurate fuel gauge reading.

My '53 is odd in that there is always power to the instruments, brake switch, horn, etc. This may be a change that one of the POs caused, or that's the way things were back then. When I'd stop the car, the needle for the fuel gauge started "dancing" and it wouldn't calm down until the fuel in the gas tank stopped rocking the float.

Regardless, I will leave it this way for now and if things get worse, then I'll have to open the cover and take a look. Thanks again.
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Cam a.k.a. CVOLVO.COM

Hi;

When the tank is somwhere between full and empty, it is completely normal that the needle moves during driving, because unlike modern cars there is no damping of the signal between the sender and the gauge on these early Volvo's. You can with some training use this jumpåing to judge how little fuel is left in the tank when you apporoach the empty level.

Your other problem with the needle indicating only 3/4 when tank is full sounds to me as a question of mechanically adjusting the floater on the sender so that the sender goes to the top/peak when the tank is full.

Good luck!

Ola of Norway
-58 PV 544 B16B
-88 240 B230K

Cam;

Sounds like an intermittent connection from the slider connected to the float to the wound resistor element. Remove, open the sender and inspect slider, and windings..clean gently... check with an ohm meter throughout entire range of float motion...possibly bend slider to give it just a bit more contact force if intermittent.

Cheers