1968 Fuel Gauge Always Reads Full

Hi:

Our gas gauge reads full all the time when the ignition switch is on or accessory position. I pulled the sending unit wire and got a reading of 8.6 ohms between the sending unit stud and ground.

I also checked the continuity between the sending unit wire and ground with a buzzer. There appears to be a circuit to ground (it buzzed). The ignition was off. I am guessing this is a sign of a broken/grounded wire. Unfortunately I have been unable to find a wiring diagram for this system.

Yesterday the gauge (on accessory) would go to full, then slowly dropped to empty, then back up to full.

The resistance reading indicates that I need to replace/repair the sending unit. I am concerned about the continuity between the sending unit wire and ground. I really hate chasing down electrical shorts!

Your thoughts?
Pat

It sounds like the wire from the sending unit to the fuel gauge may be Grounded.
Question: With the wire removed from the sending unit, Ign Sw On or Acc, what does the fuel gauge read? (It should read Empty)
If you Ground the Sending Unit wire, the Fuel gauge should read Full.

Neil

Neil:
I just pulled the sending unit. It was very corroded, so I have just ordered a Scott Drake replacement. We have a busy day tomorrow and the car is up on a lift. Will do the check when I can. I am afraid the wire is shorting out and I dread replacing it (or chasing the short).
Pat

Good news! The gauge stays on "E" with wire disconnected and accessory switch on!
thank God......I hate chasing down electrical shorts.

Pat