Steve 2009: "I think it will sit on full a long time"
Spina:
Analog sender: 90 ohms FULL, zero ohms (grounded): EMPTY
Digital sender: 120 ohms FULL, zero ohms (grounded): EMPTY
The resistor wire senders are very inefficient and the accuracy doesn't even exist.
So, if you place a jumper between ground and the center pin of the weatherpack at your gas tank, you should read EMPTY.
Use a 47 ohm resistor in place of that jumper and you should read half a tank (analog).
Use a 56 ohm resistor in place of it for the digital car, and you'll read somewhere around 8 gallons.
You can use an analog sender for the digital car, but when full, the digital gauge will show around 14 gallons instead of "F". As you consume fuel, the digital display becomes more accurate.
You should make it a practice to keep no LESS than half a tank of fuel at any given time - lower than half, the fuel pump runs hot and wears out prematurely. It's the gasoline that keeps the fuel pump cool, and in top operating condition. (corrected)
https://turbobuick.com/threads/fuel-gauge-out-of-whack.431177/