Different Gas Gauge Problem

[124Germ]

So, my problem is that my gauge reads full all the time. I replaced the sending unit with same results. When I remove the "pink" wire there is no change to the gauge, but when I ground the "pink" wire the gauge goes to empty. Today I tested the "pink" wire from the sending unit to the gauge and all test fine. I even made a separate ground to the sending units, no change.

Now I think I might have a faulty gauge?? Could there be a bad ground on the gauge itself? The other thing I could try is to run a separate test wire from the sending unit straight to the gauge and see if that changes my indications.

Thanks for your help in this weird wiring issue.

Jeremy

[spider2081]

Are you disconnecting the wire right at the sender and the gauge pegs and then grounding the wire removed from the sender and the gauge reads empty. If you did this test physically at the sender I believe your gauge is good as is the wire between the gauge and the sender.
Are you sure the replacement sender is the correct sender for your car???
Do you have an ohm meter to check the sender with.
If you connect the sender out of the tank being sure the metal cover of the sender is grounded does the needle move when you move the sender arm??? ignition key on

[124Germ]

Yes, I am grounding the wire at the sender....the gauge goes to empty. I thought an open in the sending wire would cause the gauge to go to empty, not a short. All testing is conducted with the ignition on.

I have a multimeter that I can use to read the resistance across the sending unit, I also have the old sending unit to test also. I used the old sender (out of the tank, but hard wired to ground). when I moved the float around the gauge lowered just under full and stopped. With the float in the empty position, it still read between 3/4 and full.

Is there a ground on the gauge that I'm missing? I will have to look at the manual again plus under the dash to run out the wires again.

Thanks for the feedback

Jeremy

[spider2081]

when the sender is in the empty position, arm all the way down. The resistance of the sender should be almost 0 ohms.

[124Germ]

Okay, I will take a look at it this morning. I assume the resistance should increase the higher the fuel level. Any idea what the max resistance should be when the tank is full?

Thanks
Jeremy

[124Germ]

I have the opposite results, when the float is in the up most position (full) the resistance reads almost 0. But I do know that the resistance changes with the movement of the float, so the sender is good.

I tested the wiring to the gauge and that all tested good also.

I ran a separate wire from the sender to the gauge and have the same indications.

When I have everything wired up normal and test the sender through its range, I notice that the needle on the gauge changes a little bit. As an example, the float in the full position, the needle reads past full on the gauge. With the float in the empty position, the needle read between 3/4 and full. So there is a bit of movement in the gauge as the level changes, but not as drastic as the proper reading.

So with all that testing, I have come to the conclusion that the gauge is faulty. I have never seen a gauge fail before, unless there is something else I can check and test.

Thanks

Jeremy

when the sender is in the empty position, arm all the way down. The resistance of the sender should be almost 0 ohms.

[bradartigue]

I have never seen a gauge fail before, unless there is something else I can check and test.

Check that the wiring to the gauge is hooked up right (which you may have), if you hook it wrong it will peg the gauge. If it has been that way too long it will have fried the tiny copper windings inside of it and it is toast.

Either that or you have a perpetual motion machine.

[124Germ]

The sending unit had failed on the previous owner and never replaced it for a couple years that she owned it. Could that have caused the gauge to fry?

Thanks
Jeremy

[spider2081]

If you ground the sender wire and the gauge reads empty then it should read empty with the sender if the sender reads 0 ohms in the empty position.
I had a temp gauge read funny and I found it was the ground terminal rivet was loose I could move the ground connection around on the rivet. One symptom was the gauge read different when panel lights were on. I soldered the terminal to the gauge case and that cured the problem.