MGB Register Forum

Hello can you help? Since I've owned my Mgb le I've always had problems with the fuel gauge not working. Ive replaced the sender unit and the voltage stabilizer and even checked the sender works with a meter but if I seem to get it working it only stops after a short period. Anyone else had this problem and could you shed any light on this?

Hi Mark
Given the checks you have already done and parts you have replaced, I would suspect you have a problem in the wiring between the sender unit and the fuel gauge. Unfortunately the later cars have a much more complicated wiring system so finding the problem will depend how confident you are at auto electrics and if you have a multi-meter to check out the wiring. You will need the relevant wiring diagram for an LE and quite a lot of patience to chase out the wire through several connectors. It is most likely to be problem at or within a connector and even more likely to be somewhere exposed underneath the car. You are probably looking for a high resistance joint which allows normal operation for a time but generates a bit of heat so the resistance goes up and stops sufficient current from flowing to work the fuel gauge. Alternatively it will be a bad earth which will have the same effect on the circuit.

Thanks Pete .. I'll start checking ☺

Evening Mark.
Try the old trick of shorting the connector to the sender on the tank to earth. The gauge should read full. If not there is a wiring problem. I presume the gauge is compatible with the sender.
. Vic Butler

PS.
The ignition must be switched on to carry out the test.
. Vic Butler

So how would I do that bob ?

Sorry vic ? Too much Christmas cheer

Evening Mark.
Disconnect the lead from the sender located on the petrol tank behind the right hand rear wheel , switch on the ignition and hold the lead against a metal surface. Make sure there is a good connection and get someone to see if the gauge reads full. If it does the wiring and gauge are OK.
Many years ago I fitted a new tank and sender to my 1977 BGT and the gauge has never worked properly since. With a full tank the gauge reads just over half full. I'm living with it.
. Vic Butler