How does your car know how much gas you have?



How does your car know how much gas you have?

In: Engineering

There is a sensor in the gas tank. There are several types, but the simplest is a floating device (like a rubber ball) connected by a lever to an electronic component called a potentiometer (think volume buttons on old stereos). As the gas level goes down, the floater goes with it pulling the lever on the potentiometer. The varying electricity flowing through the potentiomenter is used to power the gauge on the dash, making it go from one side to the other as the tank empties.

There is a plastic ball in the fuel tank that floats on top of the fuel. The ball is attached to a rod. The car knows the height of the ball, because it is holding the rod.

Inside the tank is a float attached to a rod. The fuel indicator is controlled by the angle of the connecting rod. So when the tank is full, the float hits the top of the tank. Likewise when running near or at empty, the float rests on the bottom of the tank. This is why when you refuel, the gauge sits at “full” for a bit and why when “empty” you can still drive for a bit.