Fuel Gauge Voltage

[tboltmike]

My fuel gauge isn't reading right. Went thru the booklet trouble shooting manual and it doesn't mention voltage from the gauge from the sensor. I have right at 5 volts with the S wire disconnected from the sensor. The sensor resistances are OK, 30 to 240 ohms.
Should the gauge be supplying 12v to the sensor? This is the original Tempo gauge, '75.
I'm suspecting wiring connections or bad gauge. The readings are the same with the old and new senders.
Thanks Mike

 

[Silvertip]

Re: Fuel Gauge Voltage

No -- the sender places 33-240 ohms of resistance across the gauge causing it to translate that into a fuel level reading. You should measure +12.6 volts on the + terminal of the gauge. The negative terminal on the gauge needs a good solid ground as does the sender shell. In fact all connections in the circuit need to be clean and tight. Corrosion = resistance. Resistance that adds to the sender resistance causes erroneous readings.