Topic says it all. I was just wondering how the fuel gauge works. Its an electrical current running to the gauge right? What is reading in the fuel tank? Is there something floating reading the level? When I turn right, the fuel reading drops, when I turn left it goes higher etc etc.

However it also reads differently from when the engine is cold, to when I've been driving around a while. If my gauge reads 1/2 tank exactly when I park it. I could come out 6 hours later, and it would read 3/8 of a tank.

 

The sender in the tank uses a float to measure the level. The gauge measures the resistance of the sender, about 90 ohms for a full tank, 0 ohms for empty.

 

In these cars... It doesn't. Even when new the gas guages were never really accurate.