Fuel Injector Cleaning

This procedure removes and cleans the fuel injectors on the 3.5L EcoBoost engine using a fuel injector cleaning kit, then reinstalls them with new O-rings to restore optimal fuel delivery and engine performance.

Warnings

Tools required

Parts

• Fuel injector O-ring kit (upper and lower seals for 6 injectors) × 1 — Use OEM specification
• Fuel rail O-ring kit × 1 — Use OEM specification
• Fuel injector cleaning solution × 1 — Compatible with GDI systems

Preparation

1. Ensure engine is cool to the touch and vehicle is parked on level ground in a well-ventilated area
2. Disconnect negative battery cable and wait 2 minutes for system capacitors to discharge
3. Remove engine cover by pulling upward on cover after removing cover screws
4. Clean debris from around fuel rail and injector area using compressed air
5. Place shop towels around fuel line connection points to catch any residual fuel

Procedure

1. 1

   Relieve fuel system pressure
   Locate the fuel pump fuse (F27) in the engine compartment fuse box. Remove the fuse, then reconnect the battery temporarily and attempt to start the engine. Allow it to run until it stalls from fuel starvation. Crank the engine for 5 seconds after stalling to ensure all pressure is relieved. Disconnect the battery again before proceeding.
   ⚠️Even after relieving pressure, some residual fuel will remain in the lines. Have shop towels ready.
2. 2

   Disconnect fuel supply line
   Using the appropriate fuel line disconnect tool, depress the locking tabs on the fuel supply line quick-connect fitting at the fuel rail. Pull the line straight back to disconnect. Cap the open line with a clean plug or shop towel secured with a zip tie to prevent contamination.
   ⚠Inspect the quick-connect fitting for damage. Replace if any cracks or wear are visible.
3. 3

   Disconnect electrical connectors and vacuum lines
   Disconnect the electrical connector from each fuel injector by pressing the locking tab and pulling straight up. Disconnect any vacuum lines attached to the fuel rail or intake manifold in the work area. Label connections if necessary for reassembly. Remove any wiring harness clips securing the injector harness to the fuel rail.
4. 4

   Remove fuel rail mounting bolts
   Locate the four fuel rail mounting bolts securing the fuel rail to the intake manifold. Using a 8mm socket, remove all four bolts completely. Keep bolts organized for reinstallation.
   Torque spec

   Fuel Rail Bolts12 Nm (9 lb-ft)
5. 5

   Remove fuel rail and injectors
   Carefully lift the fuel rail straight up from the intake manifold. The injectors will remain attached to the rail. Work the rail gently side-to-side if resistance is felt, but pull evenly to avoid damaging injector tips or O-rings. Once free, place the fuel rail and injector assembly on a clean work surface with injector tips pointing upward.
   ⚠Do not allow injector tips to contact any surface. Damage to the injector tip will cause poor spray pattern and engine performance issues.
6. 6

   Remove injectors from fuel rail
   Note the orientation and position of each injector. Using a gentle twisting and pulling motion, remove each injector from the fuel rail. Remove and discard all old O-rings from each injector (upper and lower seals). Use a pick or O-ring removal tool if needed, being careful not to scratch the injector body sealing surfaces.
7. 7

   Clean injector seats and fuel rail
   Using a non-metallic brush, clean the injector bores in the fuel rail and the injector seats in the intake manifold. Remove any carbon deposits, old O-ring material, or debris. Wipe clean with shop towels. Cover the open injector ports in the intake manifold with clean shop towels to prevent debris entry.
   ⚠Do not use metallic brushes or abrasive materials that could damage sealing surfaces.
8. 8

   Perform injector cleaning procedure
   Following the fuel injector cleaning kit manufacturer's instructions, connect each injector to the cleaning apparatus. Typical procedure involves pulsing the injectors with cleaning solution for the recommended duration (usually 10-15 minutes per injector). Verify proper spray pattern after cleaning by observing the injector output during the cleaning process. The spray should be a fine, symmetrical cone.
   ℹ️If any injector fails to spray properly or shows an irregular pattern after cleaning, replacement is recommended.
9. 9

   Install new O-rings on injectors
   Lightly lubricate new O-rings with clean engine oil or petroleum jelly. Install new upper and lower O-rings on each injector, ensuring they are properly seated in the O-ring grooves. Do not twist or pinch the O-rings during installation. Verify each O-ring sits flush in its groove without gaps or twists.
10. 10

    Install injectors into fuel rail
    Install each injector into its corresponding position in the fuel rail, matching the orientation noted during removal. Push firmly until the injector clips engage and the injector is fully seated. Verify each injector moves slightly but remains securely clipped in the rail. Install new fuel rail O-rings if equipped.
    ⚠Ensure injectors are installed in the correct orientation. The electrical connector should face outward for proper harness routing.
11. 11

    Install fuel rail assembly
    Remove protective towels from intake manifold injector ports. Carefully align all six injectors with their corresponding bores in the intake manifold. Press the fuel rail down evenly, seating all injectors simultaneously. Work the rail gently side-to-side if needed to align all injectors. Once seated, install all four fuel rail mounting bolts finger-tight, then torque to specification in a crossing pattern.
    ⚠Do not force the rail. If excessive resistance is felt, remove the rail and check for misaligned injectors or debris.
    Torque spec

    Fuel Rail Bolts12 Nm (9 lb-ft)
12. 12

    Reconnect electrical and fuel connections
    Reconnect the electrical connector to each injector, ensuring each clicks into place securely. Reinstall any wiring harness clips to the fuel rail. Reconnect vacuum lines to their original positions. Install the fuel supply line to the fuel rail quick-connect fitting, pushing firmly until an audible click is heard. Tug gently to verify connection is secure.
13. 13

    Reinstall engine cover and battery
    Position the engine cover and install cover screws to specification. Reconnect the negative battery cable. Reinstall the fuel pump fuse (F27) that was removed earlier.
    Torque spec

    Cover Screws12 Nm (9 lb-ft)

Reassembly

1. Double-check all electrical connectors are fully engaged and locked
2. Verify fuel supply line quick-connect is properly secured with no leaks visible
3. Ensure all tools and shop towels are removed from engine compartment
4. Confirm all four fuel rail mounting bolts are torqued to specification

Verification

• Turn ignition to ON position (do not start) for 5 seconds, then OFF. Repeat 3 times to prime the fuel system and check for leaks around injectors and fuel rail
• Inspect all fuel connections for signs of leakage. Any fuel seepage requires immediate correction
• Start the engine and allow it to idle. Listen for smooth operation and verify no fuel odor is present
• Check for diagnostic trouble codes using a scan tool. Clear any codes related to fuel system pressure loss during the procedure
• Perform a test drive to verify proper engine performance, smooth acceleration, and no rough idle conditions
• Re-inspect all fuel connections after test drive for any delayed leak development

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