[kldennis]

HI Guys,
I was hoping someone could help me pinpoint a break in the wire back to the tank. It has all new gauges so it should be ok in that respect. All wiring under the dash looks ok according to the wiring diagram and pictures. Perhaps I should be chasing a bad ground. Thanks in advance.

 

[vettex2]

I haven't owned a C3 since the early 80's
but
I always look for bad grounds first
continuity second
components last

 

[TimAT]

Under the left side carpet, just inboard of the door sill plate, the harness that runs to the back for the tail/turn/backup lights also has the fuel gauge wire in it. There is a connector close to the hood release from that harness. Might be worth a look there.
You might also pull the sender wire off the tank and connect a 12v testlight between that wire and a good ground. Key on, the testlight should glow and the gauge read about 1/2 scale (depends on what bulb is in the testlight). If it doesn't light at all, track that wire up to the connector and try it there.

 

[toobroketoretire]

HI Guys,
I was hoping someone could help me pinpoint a break in the wire back to the tank. It has all new gauges so it should be ok in that respect. All wiring under the dash looks ok according to the wiring diagram and pictures. Perhaps I should be chasing a bad ground. Thanks in advance.

There is a ground wire that connects to the sending unit and real often that ground wire isn't making a good connection at the sender or where it fastens to the frame.