broken strands in fuel gauge

[fgross2006]

I was swapping the printed circuit board from a used cluster I got on ebay to my cluster so I could keep my gauges and original speedometer

when removing the hollow nuts that hold the ground studs in place in the back of the cluster I had a few of them rotate and break the single strand of wire inside the gauge.

Is this fixable? This pic show 2 fuel gauges side by side. One had 2 stands soldered to each stud. the other looks like it had only 1 strand inside but both studs look like they had something soldered to them.

Suggestions on how to fix one of these and what to use?

Attachment 104990Attachment 104991

[jessesandy]

A picture of the inside of these housings would show the important parts.
Hopefully the wires broke off without damaging the meter movement windings.
Those two wire ends just need to get to the flex circuit board.

You can just solder some long pieces of wire to the broken ends of the meter movement, stick them out the back of the meter housing.
Don't use the mounting bolts for the electrical connection at all.
Make holes as needed in the gauge cluster housing so the wires stick out the back.
Then the wires could be (carefully) soldered to the flex circuit board or secured to the mount posts with some extra nuts.

If you want to try and solder to the mount studs, don't try to directly use the wire ends on the meter movement.
Try to connect some scrap/repair wire to the mounts screws then solder those pigtails to the meter movement.
Press the screws out of the plastic frame first or it will melt.
Looks like the connections were originally bonded, not soldered. It's like a micro arc welding + stamping process.
May not be able to solder to the screws at all.

Try using fine sandpaper (400) to rub the insulation off tiny wire in stead of strippers.

[fgross2006]

A picture of the inside of these housings would show the important parts.
Hopefully the wires broke off without damaging the meter movement windings.
Those two wire ends just need to get to the flex circuit board.

You can just solder some long pieces of wire to the broken ends of the meter movement, stick them out the back of the meter housing.
Don't use the mounting bolts for the electrical connection at all.
Make holes as needed in the gauge cluster housing so the wires stick out the back.
Then the wires could be (carefully) soldered to the flex circuit board or secured to the mount posts with some extra nuts.

If you want to try and solder to the mount studs, don't try to directly use the wire ends on the meter movement.
Try to connect some scrap/repair wire to the mounts screws then solder those pigtails to the meter movement.
Press the screws out of the plastic frame first or it will melt.
Looks like the connections were originally bonded, not soldered. It's like a micro arc welding + stamping process.
May not be able to solder to the screws at all.

Try using fine sandpaper (400) to rub the insulation off tiny wire in stead of strippers.

I soldered 2 single strands of copper taken from a wire I cut open and was able to solder to the stud caps and attach to the meter movement but unfortunately the gas gauge doesn't work still.

I was able to find an ebay seller selling 3 loose gauges, oil, temp and fuel for 10 bucks plus shipping so hopefully I will be able to resolve this.

[fgross2006]

So I installed the used fuel gauge I got from ebay. It functions but its way out of calibration.

Prior to this cluster problem my fuel gauge was always below E when the ignition is off and just past F when the tank is topped off. Now its right on the line for E with ignition off. And Now that I fill up the needle buries on the F side. It now appears to have 1/4 tank on the gauge when the tank is almost empty. Not a good way to drive around.

Is there a process to calibrate the fuel gauge or someplace to send it out to calibrate it?

Attachment 105167

Attachment 105168

[Walking-Tall]

Resistance range (what makes the gauge vary) from the tank's sending unit should be checked.

JACook covered repair and/or viable other-car sending unit replacement in a 2011 thread.
It's range should be "80 Ohms empty and 10 Ohms full".
In comparison, "... the '87-'93 sender is 10 Ohms empty and 165 Ohms when the tank is full."

[fgross2006]

Resistance range (what makes the gauge vary) from the tank's sending unit should be checked.

JACook covered repair and/or viable other-car sending unit replacement in a 2011 thread.
It's range should be "80 Ohms empty and 10 Ohms full".
In comparison, "... the '87-'93 sender is 10 Ohms empty and 165 Ohms when the tank is full."

the sending unit is new, installed last year and I used the exact model Jeff said to use.

This wasn't a problem until I swapped out the fuel gauge. And since the gauge was on E and not below E when it was out of the cluster I have to believe its not calibrated. maybe it got jacked in transit.

[Walking-Tall]

Everything varies. Float, float arm, float arm angle, variable resistance start/finish position, etc... checking the sender's resistance should tell you what you need to do in order for the gauge to read right or the same as it did before. Your observations tell me your gauge is seeing something like 75Ω empty and 5Ω full, instead of 80Ω empty and 10Ω full, meaning adding a 5Ω resistor would correct gauge needle positions... and/or as you indicated, getting jacked in transit, in which case a needle "adjustment" of un-jacking may help.

[jessesandy]

Here's some measurements of a gauge (isolated from sending unit, wiring, voltage regulator, etc.) to compare your gauge to.
First tested with nothing connected.
Then with one D-cell battery (1.34v) across the gauge terminals, then two D-cells in series (2.52v) across gauge terminals.
Polarity doesn't matter.
Takes about 30 seconds for needle to rise up all the way.
The gauge is from an '83. (AFAIK, the gauges are interchangeable across years and models.)

Attachment 105195

[fgross2006]

Here's some measurements of a gauge (isolated from sending unit, wiring, voltage regulator, etc.) to compare your gauge to.
First tested with nothing connected.
Then with one D-cell battery (1.34v) across the gauge terminals, then two D-cells in series (2.52v) across gauge terminals.
Polarity doesn't matter.
Takes about 30 seconds for needle to rise up all the way.
The gauge is from an '83. (AFAIK, the gauges are interchangeable across years and models.)

Attachment 105195

the picture attachment is a dead link

[jessesandy]

Sorry, tried to make one smaller picture - anyway...

Also, batteries had 1.48v with no load then went down to 1.3v when gauge connected.
Retried and it turns out AA batteries will work too. (I must have had dead batteries the first time I tried.)

[fgross2006]

Sorry, tried to make one smaller picture - anyway...

Also, batteries had 1.48v with no load then went down to 1.3v when gauge connected.
Retried and it turns out AA batteries will work too. (I must have had dead batteries the first time I tried.)

In your pics the fuel gauge needle is below E with no voltage. That should be it's home position with car off.

Mine lands on E with no power abd I think that's the issue. If the gauge were calibrated correct I know it would read right since I have a new sender in the tank.

How do I adjust the needle

[jessesandy]

I have never tried to adjust one, or even taken one apart. Looks like quite the balancing act.

(Sorry about the blurry picture.)


Looks like the (up side down) V bend in the bottom copper colored arm is meant to limit the min/max travel.

The upper arm (with the blue wire windings) is bent at the tip next to where it hooks the needle.
Maybe that was done to adjust the needle ?

[fgross2006]

I have never tried to adjust one, or even taken one apart. Looks like quite the balancing act.

(Sorry about the blurry picture.)


Looks like the (up side down) V bend in the bottom copper colored arm is meant to limit the min/max travel.

The upper arm (with the blue wire windings) is bent at the tip next to where it hooks the needle.
Maybe that was done to adjust the needle ?

I tried to gently adjust but got no noticeable change when messing with the needle and its linkages. I am 100% certain that all I need to correct mine.

[jessesandy]

Do you have any spare needles from the original ones that broke ? Maybe bend/twist the needle itself ?
How does the movement on your meter line up compared to mine ?

[JACook]

Factory fuel gauges are not at all like regular meter gauges, as you've no doubt discovered. The gauge functions
by heating a taut wire, and as it grows in length, it becomes longer and sags. The needle measures the amount
of sag. Anything you do that alters the functional length of the taut wire, will alter the function of the gauge. This
most likely happened during the original disassembly.

I wouldn't even think of repairing one of these, as long as replacements are still available for cheap. Just be a lot
more careful with the next set. And don't try to use the nut to chase the threads... That said, there are companies
out there that specialize in this kind of repair, for gauges that are not easily replaced.

[fgross2006]

Factory fuel gauges are not at all like regular meter gauges, as you've no doubt discovered. The gauge functions
by heating a taut wire, and as it grows in length, it becomes longer and sags. The needle measures the amount
of sag. Anything you do that alters the functional length of the taut wire, will alter the function of the gauge. This
most likely happened during the original disassembly.

I wouldn't even think of repairing one of these, as long as replacements are still available for cheap. Just be a lot
more careful with the next set. And don't try to use the nut to chase the threads... That said, there are companies
out there that specialize in this kind of repair, for gauges that are not easily replaced.

Thanks Jeff

I still have the ebay replacement fuel gauge in my car and the needle is still off by almost a 1/4 tank.

I sent 2 gauges out to a guy I found in a thread here that repairs gauges and retro-fits AMP gauges into VOLT gauges. He is gonna repair and calibrate the Fuel gauge and convert my AMP into a VOLT gauge.

Is there any way to calibrate the fuel gauge I still have?