E30 Zone

filled the car up last night all was fine. drove to work this morning and noticed gauge was reading empty. when i stop at junction's it moves like crazy almost with the engine rpm. there is still a full tank in tho.

just reading through old threads is there a nut on the back of the gauge that needs tightening.

Yep - either that or you need new SI Batteries.

ChemicalAl wrote:Yep - either that or you need new SI Batteries.

wot are SI batteries

If all the service indicator (SI) lights on your car work (all green, yellow, red) then I suspect that your batteries are fine, if not you'll need to change them:


If you take the clock cluster out (which you'll need to do to tighten the wee nut on the back of the fuel gauge anyway), then undo the screws on the back and then carefully take out the circuit board at the bottom, you'll see two rechargable nicad AA batteries that power parts of the cluster including the fuel/temp gauges and SI lights.

These batteries are soldered into the board, so you'll need to source spare batteries and a soldering iron (Maplins) and then get to work de-soldering and re-soldering.

I need to do this to mine, but i've never soldered a thing in my life and an scared i'd feck it up! Good luck doing yours (if it needs it).

One other thing, if your cluster needs a front fog indicator light, its obviously advisable to fit this whilst you have the cluster out.

nuts tight but still same prob gonna do batteries at the weekend.

lets know how you get on

had the exact same problem, take your rear seat base off, remove the inspection plates. the passenger side float was buggered on mine so you can try that first. unplug it, see what happens. shouldnt be erratic... then get a wire and bridge the plug. i think you ought to get a full tank of fuel reading. with nothing being erratic, if it still is. plug it back in. and try the otherside. hope this helps....

as he said, mine was jumping allover the place and turned out to be a buggered fuel sender too.