[AdamIsAdam]

ok, so here's where I'm at. First off, can anyone confirm if the `64 sending unit is a 90 ohm unit or 36? Q-S said early pontiacs were 36ohm, so maybe my 64 LeMans is also.

My tank was filled then I drove home, which should bring it to 18 gallons. I'm getting 36 ohms by disconnecting lead to sending unit and measuring across the unit (touching the lead plug and ground).

Next up is the gauge:
Volt reading into the back of the gauge is 11.8v. volts out is about 2.8v.
Then I pulled the back seat to check the flat wire connections since I had the seat out last week. While the connector from flat to regular wires had some corrosion, the volts were the same before and after the connector. (I cleaned them anyway).

More importantly, when I tried to ground the gauge, right at the gauge this time, and also at the flat wire behind the seat, I can't get it to read EMPTY, ever. It goes to FULL when the key is ON or ACC, and to EMPTY when OFF. But I can't seem to get the gauge to go to E by grounding it.

So does this mean my gauge is the problem?

PS I don't trust my gauge because I get varying readings. I'll buy an auto adjusting gauge soon. this is a sperry multi-metter, digital.

EDIT: I just noticed that Summit lists the 64 Bonneville sending unit as 0-30. I'm beginning to think my gauge is the problem.