Hope this helps some?
FUEL PRESSURE SOLENOID ON END OF FUEL RAILDESCRIPTIONFuel Pressure Solenoid (on end of fuel rail) aka: Fuel Rail Pressure Control Valve.
The Fuel Pressure Solenoid valve is screwed into the rear of the fuel rail. The solenoid controls and maintains constant rail pressure by a pulse-width modulated control current transmitted by the (ECM).
The tip-end of the FPS uses a knife-edge type high-pressure seal. The knife edge actually deforms the metal in the fuel rail in order to seal the surfaces.
The FPS must be replaced if it is removed from the rail - each replacement must establish the knife-edge seal to prevent leaks at 1600bar (23206psia).
OPERATIONIn de-energized state, the FPS valve is closed as spring tension forces the ball into the
ball-seat - spring tension limits minimum rail pressure to 100 Bar 1445psi. When the engine is started, the solenoid valve is additionally held closed by electro-magnetic force. When running, fuel pressure counteracts the magnetic force of the coil and spring tension, opening the valve. When the engine is running, the valve is always open to a varying degree, controlled by the ECM.
The ECM senses actual operating fuel rail pressure by the signal received from the fuel rail pressure sensor.
High pressure fuel in the rail flows to the ball-seat of the solenoid valve. The specified rail pressure required by the system is set by the FPS - the ECM sends a controlled current thru the solenoid, building up a magnetic force which corresponds to this specific pressure. This magnetic force equals a specific cross-sectional outlet at the ball-seat of the valve, which allows excess fuel to flow through.
Rail pressure is altered as a result of the controlled quantity of fuel which flows out the return.
The controlled excess fuel then flows back through the return-fuel line, into the tank.
*By reducing fuel at the inlet to the high-pressure pump with the Fuel Quality Solenoid valve, which reduces excess fuel through FPS valve without reducing rail pressure, the ECM can control in-tank fuel temperatures.
Leaking fuel pressure solenoid:
There should be no fuel coming out of the solenoid return line while cranking the engine. Perform the fuel rail pressure solenoid leak quantity test to determine if it is faulty. If the injectors check good, the fuel pressure solenoid should hold 870-1450 psi during engine cranking.
THE ENGINE WILL NOT START IF THE FUEL PRESSURE SOLENOID HAS FAILED!Testing the Fuel Rail Pressure control Solenoid:
Multimeter – Test internal resistance of solenoid valve windings, typical value is approximately 3.6 ohms.
Diagnostic Scanner – Check for DTC’s and monitor fuel rail pressure during all operating conditions.
Oscilloscope – Test supply voltage and earth (ground) switching signal from ECM (PWM – “Pulse Width Modulation”) Test stability of waveform.
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