typical fuel gauge/instrument cluster question
....... my fuel gauge .. when I got the car
"my gauge" and "the car" leaves a hell of a lot of room for guess work, but here's some general ramblings.
First I'm guessing from your post that you have "a car" with a separate, replaceable voltage limiter, and not built into the fuel gauge?
But for the rest of the story, ACTUALLY grounding the gauge at the fuel tank should result in the gauge PEGGING. Age, temperature, and condition of the gauge may determine how fast this happens.
So you could have a number of problems, just think about the PATH of the SIMPLE CIRCUIT
Starts out from the battery, eventually goes to the key switch, eventually to the voltage limiter AND IT'S CONNECTIONS, to and through the gauge, out the gauge down the sender wire all the way back to the rear, to the sender, it's connection, through the sender resistor, and (hopefully) to ground
THAT LEAVES A LOT OF PLACES for bad connections, rust, corrosion, frayed wires, AND
a gauge unit that because of age, etc, may be out of calibration.
So you just have to eliminate "stuff."
Ground the sender wire at the rear, and MAKE SURE that you have a good ground.
If the gauge wont' "full scale," go up under the dash and ground the sender connection RIGHT AT THE GAUGE
Any improvement? No?
Now, measure battery voltage at the limiter and be sure it's right at the same as battery voltage.
If the limiter is a "new replacement" electronic limiter, these normall output right at 5V DC. It's difficult to check an old original type, because they "pulse" like a flasher.
CLEAN the terminals. If you have a printed circuit dash, it could be an issue with the connector, and or the soldered pins onto the board traces.
Just because the limiter "was new" does not mean "was good."
If you've done all this, the gauge unit itself just might be out of whack.
IF ON THE other hand you do get the gauge to peg full scale while grounding the sender wire, then it's time to suspect:
that the sender is NOT grounded,
that the sender is hanging up/ stuck/ rusty / a cheap uncalibrated replacement/ or the float is bad, etc, etc
