So you verified the wiring ?

Rereading your post
I installed a Autometer(0 to 90 ohm) sending unit in my poly gas tank. I ran 2 wires(one from the sending unit terminal & one from the sending unit ground) to the gauge. There is also a hot wire from ign to gauge.

The gauge reads below empty....if I put second wire from the sending unit ground to frame It reads above full.
If this is the red wire that you grounded then it is working

Just an FYI here you can also read the battery 12v on that same wire.
1. Wire lifted, + meter lead attached
2. - meter lead to ground
3. 12 V



The resistance between the 2 sending unit terminals reads 60 ohms.

Is the tank empty? Sending unit arm resting on bottom of tank. If it were hanging should read 90 ohms


The document is a drawing of the wiring, the drawing shows the ground wired back to the gauge. That is not necessary, any metal of the car and frame are a ground, sheet metal screw and lug on wire will fill the bill.

Document1.doc

One last comment if the wiring is correct; the components are matched and you are reading below empty on the gauge . You need to switch the wires at the back of the gauge, the polarity is backwards.

Be sure to let us know how you make out