MGB mgb fuel guage

[philman]

i'm still working on the inop fuel guage for my b-gt. I swapped the connections around on the sending unit and the guage reads full now. The tank is full. Connections one way guage reads empty, the other way full. disconnect the ground wire and guage reads empty either way.

 

[DrEntropy]

Gotta ground the beast to have it read at all, but the ground tab on the sender should be obviously the spot-welded one. The thing is not polarity sensitive, rather a "sliding resistor" gizmo. The connections at the gauge may affect the outcome, tho. Yours is of the 'rectangular' config IIRC? Centered t'wixt tach and clock (speedo)?

 

[philman]

i'll wait until its dry and i can get it up in the air to check which connection is which. i was doing it all by feel today. fuel guage is to the left of the tach, oil pressure is between tack and speedo. of course i don't know if the dash is stock or if the previous owner made mods for auto crossing.

 

[DrEntropy]

Ahh... Mia Culpa!

The green/black should be the one going to the sender from the gauge, the green/lt. green is a voltage supply TO the gauge. It should be a 10V supply from a voltage stabiliser, not 12V. Just some preliminary bits of info to get you on the way. /ubbthreads/images/graemlins/wink.gif

 

[philman]

i have about 10 volts on the wire at the sending unit when unplugged. really i was only trying to see if i could get the guage to move, but then had the idea that one of the previous owners may have wired the sending unit backwards.

 

[DrEntropy]

10V is correct. If you can ground the green/black @ the sender the gauge should go "full". That'll give indication you have a good gauge and wiring, but the sending unit would be in question.

 

[philman]

ok, got it. this means that i have to drain the fuel tank.