Aux tank gas gauge testing

[Roscoe95]

Hi team,

I just installed a Tom's replacement aux tank and sending unit in the 72. I plumed everything and the valve seems to be working but when I switch the gauge to aux tank from rear tank, I reads below empty. What is the test for the wiring to the sending unit? (only about 2 gallons of gas in the tank, could it be it is not filled enough to register any reading?). Thanks!

 

[figo40]

not the same problem I had but the information you need is here.
http://classicbroncos.com/forums/showthread.php?t=275796

 

[spap]

Did you get the wires mixed up
hot and ground

 

[bronco t]

Make sure the ground wire on the sending unit wire harness is grounded and attached to the sending unit. My gauge did the same thing until I cleaned and re-grounded the sending unit ground wire. Plastic tanks do not ground very well.