Possible fuel gauge failure?!

[GJR]

Hi guys,

I've just finished reveneering my dash and have re-installed it back into the car. All the gauges are working except fuel.

From memory it was reading just under 3/4 of a tank before I removed the dash, but the car hasn't moved in a while so to be sure there was fuel in it I added what I had left in a jerrycan which should put it at approx half full. The gauge was still wasn't moving so I put a meter across the pair of green wires at the back. This gave a reading of 5.9V which I guess equates to approx half full.

So I guess the gauge itself has failed. I've removed the gauge wondering if there may be a loose connection inside, but it appears to be a sealed unit.

Can these gauges be opened and repared? A replacement gauge appears to be around 50 pounds but I don't really want to buy a new one if it can be fixed, thanks.

[GJR]

As an update, I've taken the fuel gauge out of the car and applied 4 AA batteries in series, (approx 6V) to the treminals at the back of the gauge, which gave a reading on the fuel gauge of around 3/4 of a tank.

So I'm confused, the gauge appears to be working when tested with AA batteries, yet when back in the car with approx 6V measured across the terminals the gauge doesn't move.

Does anyone have any ideas? Any thoughts appreciated.

[Bastian]

Maybe a silly suggestion but have you swapped the wired as a test?

[Loubaruch]

Are the terminals on the meter and the spade connectors clean, if dirty they could be offering a high resistance that could affect the reading although the voltage across the terminals may still read OK

[GJR]

Thanks for the responses.

Bastian, the spade connectors at the back of the gauge are all different sizes so they only fit one way. The gauge is fed by two green wires going to one connector and a single green/black wire to another smaller connector. There is also a third solid black wire connected which I'm guessing is an earth. I could try switching the green wires around but if that worked, and as the spade connectors are designed to fit only one way, it would mean that the wires had changed polarity wouldn't it? I'll give it a try along with Loubaruch's suggestion and see what happens. Cheers

[Loubaruch]

Hi, Dont swap the connectors, as you say they are polarity sensitive and may damage the meter. Check that the earth lead is actually earthed, as the dash has been out it is quite easy to disturb earth connections. You could run a parallel wire to a known good earth to check this.