Pumps with relief valves simply dump excess pressure back to the fuel tank. More modern systems regulate pressure by varying pump voltage or with an internal pressure relief valve. This offered an advantage of allowing fuel to cool. The fuel pressure regulator returned excess pressure from the engine fuel rail to the fuel tank. Older systems used a fuel pressure regulator in the front of the vehicle.

Fuel pressure is critical and the pump maintains it within a narrow range. Fuel enters the pump through the strainer, flows through the motor and exits under pressure. A small permanent magnet motor drives an integral pump. The pump is the heart of the fuel pump module and does the work of moving fuel from the tank to the injection system. A few have fuel senders and fuel filters that are separately replaceable. These fuel pump modules are most often available only as an assembly. They may also include a fuel filter, as part of the module. A sender unit sends a signal to the fuel level gauge to show the fuel level in the tank. The fuel pump module consists of a fuel pump, internal wiring, anti-drain-back valve and a strainer. More modern designs employ a fuel pump module. With care, failure of the fuel pump is often preventable.Įarly fuel pumps were replaceable, separately from the level sensor and pickup tube. Due to the complexity of the pump and difficulty of access, replacement can be very expensive. The fuel pump is responsible for delivering fuel from the fuel tank to the engine at the appropriate pressure required for performance demands. The pump is commonly located inside the fuel tank. Virtually all modern vehicles with internal combustion engines come equipped with fuel pumps.

Bad fuel pump module