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TR6 Fuel gauge mystery

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ceedub

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After both my fuel gauge and temp gauge quit, I replaced the regulator. The temp gauge came alive but the fuel gauge has either worked OK one day, not worked at all ( reading empty )another day or my current reading of full even after I disconnected the wiring at the sender. It would appear that the wiring has grounded out somewhere before the sender but I haven't got a clue where I might search. I have the tach and speedo out for access but can't find any wiring suspects. I'm stuck! Dr. Lucas seems to have me in a hammer lock. Thanks for any assistance.
 
Just a WAG... is it possible that the wire you disconnected from the sending unit was touching a ground when it read full?
Also, the plastic float after all these years tends to leak and fill up with fuel so the gauge always reads Empty. You can replace the plastic float with a brass one.
 
Marv, if the fuse was US wouldn't both gauges fail? Elliot, the wires on the sender are enclosed so not grounding and the sender is new and I can see that it is floating.
 
Since you have part of the dash out and can access the fuel and temp gauges, disconnect the green/black wire from the fuel gauge and switch on the ignition. Also disconnect the green/black wire from the sending unit... do not let the disconnected end touch earth. If the gauge reads empty with the wire off and full with the wire on, then the green/black wire is shorted to earth somewhere between the tank and the gauge.

If the gauge reads empty with the green/black wire connected and disconnected from the gauge, reconnect the green/black at the tank. If the gauge goes to full again you either have a faulty sending unit or you have the wires on the wrong sending unit terminals. The green/black wire goes to the terminal that will have an insulator between the sender's mounting flange and the spade terminal. The spade terminal spot welded to the flange is the earth connection. If the green/black wire is accidentally connected to the spot welded terminal the gauge will always read full.
 
I think I have found the problem. I decided to take the fuel gauge out to see where the ground fault might be. I pulled the green/black wire from the gauge and it still went to full. So the only place that it was finding ground was through the light bulb circuit since when I pulled the light bulb from the gauge, it then read empty. I happened to have an old fuel gauge in my kit and when I hooked it up, it worked fine. So something inside the gauge is haywire. I'll take it apart tomorrow and see what might be going on. Maybe one of the insulators on the spade connectors attached to the gauge is faulty.
 
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