1. Measuring the fuel level: It contains a float that rises and falls with the fuel level. The float's position is translated into an electrical signal that's sent to the instrument cluster, showing you how much fuel is in the tank on your fuel gauge.
2. Providing a ground for the fuel pump: The fuel sending unit also acts as a ground for the fuel pump. This completes the electrical circuit necessary for the fuel pump to operate.
It's a single integrated unit, meaning the float and the ground connection for the pump are contained within the same assembly. Replacing it usually requires dropping the fuel tank.
