fuel gauge not working

[DGC]

Analog fuel gauge stays at empty. Installed a new tank, fuel sending unit (spectre) and racetronix fuel pump. Parts work fine and engine runs as before. Checked wiring diagrams and find that the pink wire from the sending unit carries all the signal (relative to ground) up to blade #9 of the 18 pin instrument cluster connection in the dash. The 3-prong connector from the sending unit in the rear carries the sending unit resistance from the pink (middle) wire relative to the tan/white wire (outside pin). Reading gives 45 ohms (~half tank). There is no resistance from pink to ground. Traced pink and tan/white wires through channel in the door sill, and the 45 ohms exists at this location. Pink wire connects to pin #9 in the dash, however tan/white wire 'disappears'. From what I can determine, the problem has to do with the ground versus tan/white difference, and whether the sending unit is grounded to the frame ( or should be).

Anyone have a similar problem? and if so, how did you solve it? Considered grounding the tan/white wire, but without knowing where it connects, would rule that out.

Thanks for your help.
DGC

 

[GNVenom]

Tan/white is the fuel pump positive feed. The sending unit doesn't use that as reference.

It's the black/white wire (ground) and pink which control the signal (resistance) to the gauge.

Be sure the wire in cavity A is ground. You can use a carbon resistor, 68 ohm 1/2 watt between pink and ground to verify that the gauge is operating.

90 ohms is full, zero ohms is empty.