[Mgs] Faulty fuel gauge

[Paul Hunt]

Other than on the very first MGBs with the Jaeger gauges the ancillary 
gauges are slow acting as they are thermal using a heater to bend a 
bi-metallic strip, which takes time.

Is this a 67 with dual temp and oil gauge or separate?  If separate and it's 
only the fuel gauge that isn't working or you have the dual gauge then when 
it isn't working and with the ignition on (disconnect a coil wire to stop it 
overheating) connect a known good ground to the green/black connector at the 
tank, just long enough to see if the gauge starts rising.

If it does the wiring from there back to the gauge is OK, so move the ground 
to the body of the sender - you might have to scratch a clean bit.  If the 
gauge moves up again then the ground is bad, this comes from a bolt for the 
number plate.  If the gauge doesn't move here, but did when on the 
green/black at the tank, the sender is bad.

If grounding the green/black at the tank didn't move the gauge find that 
wire where the rear harness joins the main harness in the mass of connectors 
by the fusebox.  Connect a ground here, and if that works it is probably bad 
connections in that bullet connector.  If still no gauge movement, even on 
the cleaned bullet of the wire coming from the main harness, then you need 
to get at the back of the fuel gauge and connect a ground to the green/black 
(not the light-green/green).  If the gauge works now there is a break 
between it and the connector by the fusebox but that is unlikely on a 67. 
If still no movement check for 12v switching on and off about once per 
second (that is the action of the ironically named 'stabiliser').  If you 
see that both terminals of the gauge, or it is definitely on the 
light-green/green terminal but not the green/black, the gauge is faulty.

If on neither and you have separate gauges and the oil gauge is OK the 
light-green/green between the fuel and oil gauges is broken.  If none of the 
separate gauges are working, or you have the dual gauge, either the 
stabiliser itself will be faulty (you have 12v on the green at the 
stabiliser) or the 12v fused ignition supply (green wire) feeding it is 
broken (no 12v at the stabiliser green).  The 12v supply to here comes 
direct from the fusebox, and goes on to feed the tach and heater switch.  So 
if these are working it must be the stabiliser or the connections to it.

PaulH.

----- Original Message ----- 
> Noticed recently that my fuel gauge on my 67 BGT hasn't been working
> correctly.