what would cause the fuel guage to read at approx the 5 oclock position at full and and then at empty read at approx 3/4 (approx) 1 oclock at empty? this is on a origional guage


then i have a OER guage i just got off ebay and this guage reads 4 0clock at empty and goes to about 10 oclock on full? and i tried it with and without the resistor on this one


all the wiring is fine and the sender unit checks out and i have another oem guage that works

and i also used the search function and cannot come up with what may cause this.

The reading on the gas gauge is a function of the resistance (to ground) on the sender line (assuming the gauge has both 12 volts and a proper ground)

0 ohms = empty
45 ohms = half full
90 ohms = full
more than 90 ohms = past full

Since you've ruled everything out, and it still doesn't work, you need to start over.

Use a jumper wire to ground the tan wire in the trunk.

Gauge reads empty = pull the tank and fix the sender.
Gauge reads anything else = continue

Use your jumper wire to ground the tan wire at the connector for the rear harness, it's just above the drivers side kick panel.

Gauge reads empty = fix the wire from there to the back of the car.
Guage doesn't read empty = continue

I can't remember the year of your car, and you didn't say in your post, and your profile is not filled out, so...

You need to get at the back of the gauge and measure voltage between the +12 connection and the ground connection, both right at the gauge. 67-68 is hard to do, you have to pull the cluster, and doing so removes the ground connection, so you have to run another ground, with the cluster hanging out. 69's I think are easier.

If you have (for sure) good 12 volts and ground actually at the gauge, ground the sender connection a the gauge.

Gauge goes to empty = keep looking
Doesn't = Try another gauge.

At some point, you may want to get a 100 ohm resister and repeat some of these tests using that in your jumper wire. Gauge should read full.

Jim everything on car is fine as i have a guage that already work's, my main question is what would cause the guages these other guages to read the way they do?

these three guages i have i am bench testing them with another sender and all 3 of them work while i manually move the float from empty to full it's just that 2 of them are way off calibration 4 to 10 oclock empty to full and the other is 1 to 5 oclock empty to full, the 3rd one reads were it should empty to a little past full when it's full, all done on same bench test.

is there something inside the gauge that goes bad? is there a way to recalibrate it?

since the miscalibrated ones all seem to have the same amount of swing to them, 1 to 5, and 4 to 10. Pull the needle off and reposition it at empty when the sender is at the empty postion during your bench test.