Mechanical Returnless Fuel System (MRFS) - Dual Speed
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The dual speed MRFS uses a fuel tank with reservoir, the fuel pump, the fuel pump control module, the fuel pressure regulator, the fuel filter, the fuel supply line, the fuel rail, and fuel injectors. For additional information on the fuel system components, refer to ENGINE CONTROL COMPONENTS . Operation of the system is as follows:
- The fuel delivery system is enabled during crank or running mode once the PCM receives a crankshaft position (CKP) sensor signal.
- The fuel pump logic is defined in the fuel system control strategy and executed by the PCM.
- The front inertia fuel shut-off (IFS) switch is used to disable the voltage to the fuel pump control module in the event of a collision. The front IFS switch is a safety device that should only be reset after a thorough inspection of the vehicle following a collision.
- The PCM commands a duty cycle to the fuel pump control module. The fuel pump control module reports diagnostic information to the PCM.
- The fuel pump control module controls the voltage to the fuel pump (FP) based on the duty cycle request from the PCM. Voltage for the fuel pump is supplied by the PCM relay. For additional information refer to FUEL PUMP (FP) CONTROL MODULE for 2.5L, FUEL PUMP (FP) CONTROL MODULE for 3.0L. Fuel Pump Control and Fuel Pump Monitor.
- The fuel injector is a solenoid-operated valve that meters the fuel flow to each combustion cylinder. The fuel injector is opened and closed a constant number of times per crankshaft revolution. The amount of fuel is controlled by the length of time the fuel injector is held open. The fuel injector is normally closed, and is operated by a 12-volt source from the fuel pump relay. The ground signal is controlled by the PCM.
- There are three filtering or screening devices in the fuel delivery system. For additional information refer to FUEL FILTERS .
- The FP module contains the fuel pump, the fuel pressure regulator, lifetime fuel filter and the fuel sender assembly. The fuel pressure regulator is attached to the FP module and regulates the pressure of the fuel supplied to the fuel injectors. The fuel pressure regulator controls the pressure of the clean fuel as the fuel returns from the fuel filter. The fuel pressure regulator is a diaphragm-operated relief valve. Fuel pressure is established by a spring preload applied to the diaphragm. The FP module is located in the fuel tank.