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My fuel guage is acting erratically.

- it often shows empty when I know there is gas in there;
- it will suddenly correct itself for awhile
- and then revert back to empty again.
-and then repeat this process again.

Feels like an electrical problem.

Any suggestions,

thx, PeterCS

Sounds like a corroded connection indeed. No further issues with instruments or instrument lighting? Easiest check is at the side of the fuel sender pick up that is on top of the rhs fuel tank. If you remove the rear seat bottom (just two 10mm bolts at the front) you will find a black cover, underneath you will find the sender and the plug that hooks it up to the wiring loom. Check, clean, on and off a few times, not much mor you can do apart from a visual check on the wiring.

If that doesn't work it may be at the other end, either the connector that hooks up to the back of the instrument cluster, or the flexible circuit at the back of the cluster itself. From underneath you may be able to remove and refit the connector that's pretty much behind the gauge, removing the cluster for further inspection is more work.

I had it on my e30. Took out the floater in the tank, which was corroded. Now it always shows 15 liter less. So on a filled up tank the vauge shows 40 liter.

Oh right another suspicious component!

After hearing that there can be corrosion problems with the sender, I removed it (see picture).
- Seems in good shape to me;
- I can feel the tumbler moving up and down inside the chamber
- have cleaned the electrical connections

Anything else I should do or check?

thx
PeterCS
82 Baur
74 2002

When you have it out, just hold it upside down, with the ignition on.

See what the gauge does. Upside down should read the gauge as full.

I had exactly the same problem. I took the sender apart & there's a very thin wire that runs from the top, and the base & back up. It had snapped right at the top. I re-soldered it & although it was better it was not very accurate, I assume I'd altered the resistance with the solder.

In the end I bought a 2nd hand one from a guy on here. Solved it instantly...

The gauge did not show full when I took it out and turned it upside down.
Recleaned the wiring.
Now shows empty with the yellow "empty" light on. (Wires crossed?)
Time to get a replacement?
Peter

What happens if you short circuit the plug that goes onto the sender? No risk or sparks, no worries, but I believe disconnected (or wire broken in sender) it should read empty, and shorted it should read full.

How do I short circuit the sender? Need instructions.
Many thanks, Peter

Short circuit the plug, use a short piece of wire to connect both pins inside the connector with each other. Gauge works on resistance value that you reduce to zero by doing this.