hi all, the i recently fixed my original gas gauge as it was never reading full the whole system is completely adjustable for offset and gain, it's pretty neato here is what i did i removed the sending unit from the tank and the gauge from the dash and connected them up outside the truck on a large cardboard so i could draw lines for float position reference. see attached photos full..half...empty_gauge step 1 - make sure your sending unit will read about 0 - 30 ohms full to empty, it's okay if it's not perfect, as long as it is consistent. step 2 - without power applied, turn your dash gauge upside down and see that the needle slowly falls up to beyond full, and then flip it back and see the needle falls slowly to beyond empty, the needle is free floating correctly step 3 - wire up the sending unit and gauge for the same circuit as installed. step 4 - make some marks on the cardboard for the full, half and empty positions for the sending unit so that you can come back to the same positions to see progress towards your desired adjustments step 5 - carefully loosen the nuts on the gauge and jiggle the position of the coils until you get the needle just right for the float positions step 6 - don't over tighten the nuts and double check, it should be possible to get nice consistent results
The sending unit should be close to 0-30 ohms for the 50-53 chevy trucks other sending units could be different ranges. The needle in the dash should be able to free fall beyond empty with gravity, if it gets stuck you must fix that issue first.
