fuel gauge issue

[Felipe Acosta]

Hey guys, I have a 73 c10 with 307 engine. I have had trouble with the gas gauge from the git go. I changed the gas tank and installed a new sensor. I tested the sensor and the gauge before installing the new parts on the truck. The gauge goes past FULL. How do you check for a bad ground? What else could be wrong?
Thanks in advance.

 

[Rumbledawg]

does the gauge go to 3:00?
had the same prob wit mine. the pink sender wire between the switching valve and dash switch was pinched grounding out the circuit.
does it look like this?

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after fixing the wire

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[Felipe Acosta]

Thanks for the reply. That is exactly what it looks like. I cancelled one of the tanks. Could this have caused the problem? What do you suggest I do?

 

[Bextreme04]

Thanks for the reply. That is exactly what it looks like. I cancelled one of the tanks. Could this have caused the problem? What do you suggest I do?

The gauge reading all the way full like that means you have an open in the circuit. So you either didn't connect the right wires or something got broken or disconnected when you deleted the dual tank. The dual tank option is an additional wiring harness that runs from passenger side to drivers side and connects to a firewall plug, both sending units, the switching valve, and the original pink sending unit wire. You should be able to remove everything for the aux tank without cutting anything and the entire aux tank harness comes out as a single harness. The pink wire will then connect directly to the sending unit. The ground from the sending unit then comes off the sending unit and screws directly into the frame. If that connection is dirty, corroded, or missing you will have this issue also.

 

[Bextreme04]

If the sending unit wire was grounding out directly onto the frame or something it would read all the way empty

 

[Felipe Acosta]

Thank you for the reply,
I grounded the sending unit and the I connected the tan wire to the other connection in the sending unit. I followed the tan wire and it went straight to the firewall. Is there anything I need to do with the tank switching valve wiring? BTW, the wire colors are Tan, Tan white, Blue and Green. Any help would be appreciated.