Fuel Rail

WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

The fuel rail distributes low pressure fuel from chassis supply line to each fuel injector. Fuel pressure at top of each fuel injector is maintained within 1 percent of other fuel injectors at all times, done by nearly symmetric flow paths. The fuel rail is also designed to have minimal flow restriction by increasing cross-sectional flow area and reducing flow path length. The fuel rail contains several other components that perform crucial functions. See Figure. These include:

Injection Pressure Sensor

Measures the pressure of fuel near fuel injectors. This signal is used by PCM to adjust fuel injector pulse width and meter fuel to each cylinder.

Engine Fuel Temperature Sensor

Measures pressure of fuel near fuel injectors. This signal is used by PCM to adjust fuel injector pulse width and meter fuel to each cylinder.

Low Pressure Solenoid Shutoff Valve

Isolates fuel rail from upstream fuel system when engine is OFF. This minimizes the amount of fuel available to flow through fuel injectors when engine is off or leak from a damaged fuel rail during and after a crash. The valve is controlled by PCM fuel shutoff valve circuit and contains an inertia switch. The valve is only on for one second after a key-on or whenever CKP signals are being received by PCM.

Schrader/Service Valve

Provides a service port to low pressure fuel system. This valve is needed to relieve pressure in system before and during service. This valve could also be used to monitor pressure near injectors during diagnostic procedures.