Question
I have a 356B, 1962; it’s a T-6 body. It had a gas tank with the bottom-mount sender. I bought a new tank which has the sender on the top. Along with the tank I had to purchase a new sender. I fit the sender in the tank, but now the fuel level in the dash instrument goes to the end: it doesn’t work. What do I do now? — S. Turner, Cypress Beach, CA.
Answer
It sounds like there is a ground problem. If you look at the wiring diagram, you’ll see the sender is grounded on one side; the ground is actually made through the sender screws. You may have had your tank powder coated, and the screws may not be making a good ground.
The new top-mount sender is an entirely different design than the old bottom-mount sender: it is the float-arm type. If you were to measure the new sender, the resistance reading is 200 ohms in full position and 6 ohms in the empty position. The older bottom-mount sender was 107 to 2 ohms, and the dash instrument had a red “R” hash mark for tank reserve indication. Ideally, you will want to have your instrument recalibrated; however, your present instrument will still give reasonable fuel level readings.
As for wire connections, you can connect the same wires as were used on the old bottom-mount tank. Remember, the brown wire is always “ground.”
General notes: in the wiring diagram for your car, you can count thirty-five places where components are grounded. Some components need to touch a good clean mounting surface. In the front trunk, on each side, only a sheet metal screw is supposed to make contact for blinker lights and horns; be sure there is good contact there.
Specific note: 356B T-6 vehicles using the bottom-mount sender also have unique markings on the fuel level gauge.
Regards,
Brad Ripley
