67-72 Chevy Truck fuel gauge diagnostics 101

[VetteVet]

More often than not the cause of a 1/4 tank reading is a bad resistor on the back of the gauge. I would try the sender sweep first and if it checks out then look at a new resistor.

[TBONE1964]

Originally Posted by VetteVet

More often than not the cause of a 1/4 tank reading is a bad resistor on the back of the gauge. I would try the sender sweep first and if it checks out then look at a new resistor.

Thank you Vette again. I am thankful that you can/will add your own experience to this thread. My thought was to get some diagnostic procedures out there that someone can reference and help solve there issue.

Is this a common problem that you see on your end? I test each and every fuel gauge for a complete empty to full range and I have not had one to date that would not read past 1/4 on the gauge.

Interesting, I have a drawer full of these resistors, red, orange and blue and they range in ohms from 95 - 108 and the color does not have make much difference. I even have they early wrapped wire resistors and they all read around 100 ohms give or take 5.

I am wondering if you have a bad resistor that restricts a gauge from going past 1/4, what would the ohm reading be then?

Good stuff here.

Take care,
Tom