Ford E7FZ-9C968-A Regulator - Fuel Pressure

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The fuel pressure regulator in EFI models serves to maintain consistent fuel pressure by introducing a calibrated restriction downstream of the injectors, allowing a portion of the fuel to return to the tank. This ensures constant pressure at the injectors, with the regulator utilizing engine vacuum, an internal diaphragm, and a spring to adjust the restriction based on engine demands. Acting as a check valve, the regulator closes the restriction path when the fuel pump is off, trapping pressurized fuel for quick engine restarts. Proper regulator operation depends on an unobstructed fuel flow, an open return path, and a reliable vacuum signal from the intake manifold. Failures in the regulator, such as contamination, vacuum diaphragm leaks, or valve malfunctions, can lead to overpressure or underpressure conditions. Tests include an overpressure test to identify unwanted restrictions, an underpressure test to diagnose pump or supply line issues, a demand regulating test to address fuel-rich conditions, and a regulator check valve function test to isolate problems with the regulator, fuel injectors, or pump check valves.

Depressurize the fuel system and remove shielding as needed. Remove the vacuum line at the pressure regulator. If necessary, disconnect the fuel return line from the regulator. Some engines use two standard hex head bolts to retain the regulator instead of the Allen" head screws. Remove the three Allen3 head retaining screws from the regulator housing. Remove the pressure regulator assembly, gasket and 0-ring. Discard the gasket and check the 0-ring for signs of cracks or deterioration. Clean the gasket mating surfaces. If scraping is necessary, be careful not to damage the fuel pressure regulator or supply line gasket mating surfaces. Lubricate the pressure regulator 0-ring with light engine oil. Do not use silicone grease; it will clog the injectors. Install the 0-ring and a new gasket on the pressure regulator. Install the pressure regulator on the fuel manifold and tighten the retaining screws to27-40 inch lbs. (3-4 Nm) for all engines except the 4.0L engine, which is tightened to 70-97 inch lbs. (8-11Nm). On the 2.3L engine, install the fuel manifold shield and tighten the bolts to 15-22 ft. lbs. (20-30 Nm). Install the vacuum line at the pressure regulator. If removed, connect the fuel return line. Build fuel pressure in the system by turning the ignition ON and OFF (without starting the engine) at least five times. Leave the ignition ON at least 5 seconds each time. Check for fuel leaks.

The regulator utilizes engine vacuum, an internal diaphragm, and a spring to adjust the restriction based on engine demands.