Fuel Gauge Needle at 3 o'clock

[kam]

Replace the sending unit in my '76 Vega and when I hit the key the needle went to 3:00 and stays there whether the key is on or off.

I checked the voltage at the connector in the hatch and it reads 8 volts. I also checked the ground and it's good.

I looked through my service manual and wasn't able to find any troubleshooting or wiring diagrams that would assist me further in figuring this out. Has anyone had experience with this or know how I can resolve this?

Thanks,

Kerry

[cjbiagi]

You say this happened after changing the sender in the tank? How was it before you did this?

[spencerforhire]

GM fuel gauges read resistance to chassis ground from the sender; an open circuit will read over full and a direct short to ground will read below empty. By "3 o'clock position" I presume you mean over past full? If you connect a jumper wire between the tan sender wire and a good ground, the gauge should go all the way down to empty.
A bad ground wire on the sender plug can cause the same symptom, but then the fuel pump wouldn't operate either.

[kam]

Yes, you are assuming correctly, the needle is past Full. I will connect a jumper as you described to see of the needle goes to empty.

Also, it must not be a bad ground on the sender plug as the fuel pump operates fine.

[kam]

OK, I connected a jumper between the tan wire and a good ground and it went to EMPTY just as you said. Then, of course disconnecting the tan wire from ground take the needle back to the 3 o'clock position.

What does this tell me? does this help pinpoint where the problem might be?

Thanks,

Kerry

[spencerforhire]

All that really tells you is that the wiring and gauge are OK; now presuming the ground wire is good(you stated that the fuel pump works) all that leaves is a bad sender. The sender can be tested out of the tank by connecting a meter set on ohms to the wire terminal and the body of the sender itself; when you swing the float down the resistance will approach zero, and when you lift it all the way up it will read something like 100-200 ohms.