Quote:
Originally Posted by 65-72 chevytoys
Now the gauge reads empty, so I think it is grounded out somewhere.
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The opposite would happen. The tan wire should be thought of as a negative or "ground wire". The way the system works is that the gauge has a constant 12V power to one side of it. The other side (the tan wire) is the negative. Basically the tan wire runs from the gauge back to the sending unit to complete the circuit. The sending unit varies resistance and regulates the amount of "ground" that gets to the gauge. When the tank is full the sender is at top and giving 0 resistance which is considered a good closed circuit showing a full tank. When the sender is down it creates 100% resistance and the tan wire doesn't get a ground. This causes and "open" circuit and the gauge goes to empty.
So keeping this in mind, if the tan wire is grounded out to the frame, this would complete the circuit (before it had a chance to get to the sender) and send the fuel gauge to full. If the wire is broken fully in two that would cause an open circuit and send the gauge to empty.
If the gauge is stuck at empty you should be looking for a broken wire, not a grounded out wire. That is why I suggested for you to PURPOSELY ground the tan wire and see if the gauge goes straight to full. Hope this makes sense.