The Ford 3C3Z-9T517-AG Fuel Pressure Regulator "Blue Spring" Upgrade Kit is the genuine Motorcraft/Ford OEM service update engineered specifically for 2003–2007 Ford Super Duty trucks, Excursions, and E-Series vans equipped with the 6.0L Powerstroke diesel engine. Designed to replace fatigued factory regulator hardware on the engine-mounted secondary fuel bowl, this factory-revised kit includes the stiffer blue regulator spring, a redesigned cast regulator housing cover, internal valve plunger assembly, and all necessary fluorocarbon seals to increase fuel rail pressure by 10–15 PSI.

Quick Specs & Kit Inclusions

• Application: Engine valley mounted secondary fuel filter bowl pressure regulator rebuild & upgrade
• Operating Pressure Gain: Increases baseline fuel pressure by +10 to +15 PSI (targeting a consistent 60–65 PSI operating range)
• Manufacturing Standard: Genuine Ford Motorcraft Original Equipment Manufacturer (OEM) component
• Emissions Status: 50-state legal (direct mechanical replacement)
• Direct Interchange Part Numbers: Ford 3C3Z-9T517-AG, Motorcraft 3C3Z9T517AG, Navistar 1843063C92
• What's in the Box: (1) Upgraded OEM Blue Fuel Pressure Regulator Spring, (1) Cast Aluminum Regulator Housing Cover, (1) Brass Regulator Plunger Valve & Sleeve, (1) Molded Viton Face Gasket, (4) Internal Port O-Rings, (1) Poppet Valve Retaining Grommet, and (4) T27 Torx Mounting Screws

Problem Solved: Curing Fuel Pressure Drops, Cavitation & Injector Damage

On 6.0L Powerstroke HEUI engines, fuel is not just combustible energy—it serves as the hydraulic cushion that absorbs the rapid reciprocating stroke of the internal fuel injector intensifier piston. The original factory regulator spring fatigues over time, allowing fuel pressure to drop under 45 PSI (and often below 35 PSI during heavy throttle and towing). At sub-45 PSI pressures, fuel vapor bubbles form (cavitation), removing the protective liquid cushion and causing the metal intensifier piston to smash directly against the injector nozzle body. This leads to premature injector scoring, cracked tips, spool valve stiction, erratic idle, and costly injector failure. Installing the genuine Ford 3C3Z-9T517-AG restores and elevates fuel pressure to a stable 60–65 PSI, eliminating cavitation, smoothing idle quality, and extending fuel injector service life.

Fitment

• 2003–2007 Ford F-250 Super Duty 6.0L Powerstroke Turbo Diesel
• 2003–2007 Ford F-350 Super Duty 6.0L Powerstroke Turbo Diesel
• 2003–2007 Ford F-450 Super Duty 6.0L Powerstroke Turbo Diesel
• 2003–2007 Ford F-550 Super Duty 6.0L Powerstroke Turbo Diesel
• 2003–2005 Ford Excursion 6.0L Powerstroke Turbo Diesel
• 2004–2010 Ford E-Series Vans (E-350 / E-450) 6.0L Powerstroke Turbo Diesel
• 2004–2008 Ford F-650 / F-750 Super Duty (VT365 Engine)
• 2003–2007 International / Navistar VT365 & MaxxForce 5 Engines

Safety & Depressurization: Park the vehicle on level ground, switch off the ignition, and disconnect both negative battery cables. Slowly loosen the secondary engine-valley fuel filter cap (24mm socket) to vent trapped residual pressure and allow fuel to drain down. Access & Removal: Place absorbent shop towels directly beneath the regulator housing on the side of the secondary fuel filter bowl. Using a T27 Torx driver, remove the four (4) retaining screws holding the regulator cover. Hold pressure against the cover while removing the final screw, as internal spring tension will push it outward. Internal Component Extraction: Remove the factory cover, weak spring, brass piston, and internal valve stem grommet. Suction or wipe out standing fuel and residual sediment from the cavity using lint-free shop cloths; inspect the female bore walls to verify there is no severe gouging. Seal Lubrication & Placement: Lightly coat all new Viton O-rings and seals with clean engine oil or clean diesel fuel. Install the new valve grommet into the internal housing seat. Seat the molded perimeter face gasket into the machined channel of the new Ford cast regulator cover, verifying it sits flat without stretching or twisting. Spring & Plunger Reassembly: Place the new brass regulator piston into the housing sleeve, followed by the new blue regulator spring. Align the new cast cover over the spring and push it square and flush against the fuel filter bowl body, ensuring the perimeter seal does not roll or pinch out of its groove. Torque Target: Hand-thread the four (4) included T27 Torx screws to ensure clean thread engagement. Tighten the screws evenly in an alternating, crisscross pattern using a 1/4-inch drive torque wrench to 45–55 in-lbs (5–6 Nm). Do not over-torque, as the aluminum fuel bowl housing threads strip easily under excessive leverage. Filter Cap Torquing: Verify the secondary fuel filter cap O-ring is in good condition, lubricated, and torqued to 19 ft-lbs (25 Nm). Priming & Leak Verification: Reconnect the negative battery terminals. Turn the ignition key to the "RUN" position for 30 seconds without cranking the starter to allow the electric fuel pump to prime the bowl, push fluid through the new regulator, and bleed trapped air. Repeat this key cycle 4 to 5 times. Inspect the regulator cover perimeter and surrounding engine valley for zero leaks before starting the engine.