Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - Petrol gauge has stopped working?

The needle on my petrol gauge is laying flat but I know there is fuel available. How easy is this to fix and where do I start looking? I think the gauge is OK but maybe a bad connection somewhere?
I have a 71 mgb roadster converted with a SD1 V8.


A Butterworth

Sounds like a bad ground to me!
Check out Rick Astley's website on MG electrical (instuments) for some direction on troubleshooting.
Graham Creswick

Start with the fuses 'tho

Happy Christmas

All the following relates to the standard setup.

If it's the fuse the tach, brake lights, reverse lights, indicators etc. will also be non-functional.

If not that, briefly connect a known good earth to the green/black at the tank with the ignition on and see if the needle moves. If so everything up to that point is OK. Then connect the good earth to the body of the sender, cleaning an area if necessary. If the needle moves again then it is the ground to the sender that is bad, this comes from a number plate bolt in the boot and also feeds the pump and reverse lights. If the needle doesn't move the sender is faulty.

If the needle didn't move in the first place locate the bullet connector where the green/black from the rear loom joins the main loom, in the mass by the fusebox, check the connections are clean and solid and try your earth in each of the three holes with wires. If the needle moves now there is a break between there and the sender.

If still no movement earth the green/black on the back of the gauge. Careful here as the other terminal, light-green/green, has pulsing 12v on it and grounding this *will* blow a fuse. If the needle moves now there is a break between that point and the connectors by the fusebox.

If still no movement check for pulsing 12v, about once per second, on the light-green/green and green/black terminals of the gauge. If on the former but not the latter the gauge is faulty.

If on neither check the green and light-green/green terminals of the voltage stabiliser, which should be screwed to the firewall on the RH side. If on both there is a break between the stabiliser and the gauge. If on the green but not the light-green/green the stabiliser is faulty.

If on neither there is a break between the stabilser going back towards the fusebox. Early 71s were the last link in a chain and immediately after the tach, so if the tach is OK there is a break between the tach and the stabiliser. On later 71s the feed went from a 4-way bullet connector behind the dash to the stabiliser to the tach, so in this case if the tach is OK the feed to the stabilser should be also.
Paul Hunt

This thread was discussed between 22/12/2004 and 23/12/2004

MG MGB GT V8 Factory Originals Technical index

This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.