MGB Fuel Guage Inop, 64 MGB

[Jayrz]

Jaeger guage, sits on empty.

Wiring going into the back of it is a single yellow, a pair of wires Green with black tracer that are buckled together to fit a single spade, then another single green wire with a black tracer.

I have found several things mis wired on the car that were easily corrected. Anyone know the correct orientation of these three? Is there a way to test the fuel guage to make sure it is not just dead?

Thanks in advance

Jay

 

[dklawson]

1964 was the transition year for gauges on a lot of BMC cars. Is this the Jaeger gauge with the bouncy needle (jumps right up when you switch on the ignition) and no voltage stabilizer behind the dash? I suspect it probably is.

If this is the bouncy gauge, look carefully at the terminals on the back. One should have a "T" stamped next to it, the other should have something like a "B" stamped near it. The green/black wire from the sending unit (TANK) should go on the "T" terminal. A switched 12V supply (typically a solid green wire) should go on the "B" terminal(from the BATTERY). Sometimes power is taken from the "B" terminal and routed elsewhere. Nothing else should be on the "T" terminal... only the wire to the sending unit.

Those early gauges MUST have a good ground connection or they will not work. Their sending units also work in a different direction than the later gauges with the voltage stabilizer. The early senders have a "nominal" range of 0 Ohms = empty to 90 Ohms = full. If you disconnect the green/black wire from the "T" terminal on the gauge and switch on the ignition, the needle should jump to (above) full. Again, the gauges with the voltage stabilizer are different.

 

[Jayrz]

Doug,

Thanks, using this I verified it was wired correctly by disconnecting the T wire and it jumped to full. Therefore my problem is the sender. All I did was try changing the wires on the sender to the opposite wires spades and,,, bingo! I now have an operating fuel guage.

Now how accurate it is I don't know, just happy the dang thing works.

Thanks again.

Jay

 

[dklawson]

Excellent! I'm glad you got the gauge working.

If you want to fine tune the accuracy, visit the MGA Guru web site. Barney Gaylord has several very detailed pages on how to calibrate the early fuel gauge at home. It's a great web site.
https://www.mgaguru.com/
Use the search field on the opening page to find "fuel gauge". Follow the first link/hit. On the page that opens use the arrows at the bottom of each page to move forward.