Fuel gauge question.

[timalabim]

Is the fuel gauge just measuring Ohms from the sender?

I was having a problem with my dash fuel gauge not going to full even though the sender tested OK. I bypassed my dash fuel gauge to hook to a NMEA 2000 network and read off my Lowrance fish finder fuel management option which worked fine and showed perfectly 100% full when the tank was filled.

I later discovered that I had a charging system issue as well. So I did have a lower than usual voltage while running. Could the low fuel gauge reading been related to the charging system issue?

Could low voltage give me a faulty reading on the dash fuel gauge?

I did still have the low fuel reading even with a fully charged battery, but now I wonder...

I know the answer would be to hook the dash gauge back up, but I did kind of physically abuse the gauge to force it to the full mark once I knew the sender was OK, but before I knew I had a charging system issue. I also can't just replace the fuel gauge because the dash is a 1 piece modular unit.

 

[Silvertip]

Re: Fuel gauge question.

Battery voltage feeds the gauge. The sender is a variable resistor that varies the voltage operating the gauge movement. As fuel level changes, resistance in the circuit changes, and the meter responds to those changes. So no, it is not measuring resistance -- it is measuring voltage as the result of a resistance change. Since the gauge is calibrated to respond with normal battery voltage, yes, low voltage will cause the gauge to read incorrectly.