One more thought on this full indication ....
The Runtz is a dropping resistor that drops voltage from 12 to 6. I am guessing that there is no current involved in the fuel guage sensing device. If you have a full tank, the sending unit will allow the meter to see 6 volts ....
if you have an empty tank it will see 0 volts ...
if your tank is half full it sees 3 volts, etc.
If you put 12 volts on the guage without a dropping resistor I doubt that anything would fry because there is no current involved. If you do not have a dropping resister and the tank is empty, then the meter will still see 6 volts and think it is full.
You may want to verify that you have a dropping resistor in series. Hope this makes sense.
