The fuel pump module consists of a fuel pump, internal wiring, anti-drain back valve and a strainer. A sender unit sends a signal to the fuel level gauge to show the fuel level in the tank. They may also include a fuel filter, as part of the module. Modern vehicles normally use electric fuel pumps, located inside the fuel tank. These pumps are complex and can be difficult to access. This often makes replacement very expensive. Fortunately, fuel pump failure is often preventable.