Replacing/Inspecting Fuel injectors

ID: 161146

Description: Applicable to all engines (H4D and H4Bt or M281...

Steps:

  1. Open the trunk.
  2. Remove the trunk carpets.
    3. Step image
  3. Unscrew the 6 T50 screws by hand or using a wrench and a socket.
  4. Lift and set aside the engine hood.
    5. Step image
  5. Disconnect the fuel injector's connectors.
    6. Step image
  6. If only inspecting of the fuel rail/injectors: skip this step and do not disconnect the fuel hose: the fuel ramp can rotate freely and the hose is slightly flexible. This will avoid to flush the fuel rail's fuel volume to do this routine check.
  7. Fire hazard: fuel may run out of the hose and/or the fuel ramp ! Please take the necessary precautions to avoid any incident.
  8. Undo the security clip using a flat head screwdriver.
  9. Disconnect the fuel supply hose.
  10. Reinstallation: respect the security clip's orientation, indicated by a foolproof.
  11. Make sure the hose is properly reconnected by pulling firmly on it. Someone found themselves on the side of the road because their hose had come off.
  12. A poorly connected hose seems to cause symptoms identical to clogged injectors. After my hose accident, my engine became smooth again as I initially expected after cleaning the injectors (much less vibrating).
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  13. Unscrew the 2 8mm bolts holding the fuel rail.
  14. Pull straight the entirety of the fuel rail upside. You may rock the fuel rail slightly to help it get unstuck.
  15. The second image show what a clean H4D's (Deka/Siemens) fuel injector looks like. The 6 holes are visible and free.
  16. If one or more injectors where to be cleaned, please refer back to step 4 to disconnect the fuel rail entirely.
    17. Step image Step image
  17. Undo the clip holding the injector to the fuel rail by slightly spreading it and then sliding it.
  18. Pull the injector to extract it. You may need to do gentle rocking/rotating motions to loosen it: the seal will probably be dry due to prolonged contact with fuel.
  19. Reinstallation: make sure that the clip makes a square shape, exactly as it was when you removed it. Pull the injector slightly to place the clip perfectly in the groove intended for this.
  20. Reinstallation: torque the 2 8mm screws at 10 N.m.
  21. Reinstallation: ideally, you should replace the seals. Lubricate the seals using a drop of engine oil (or a finger and some silicone spray) to make for easy and perfect reinsertion. (Of the injectors on the rail and when reinstalling the assembled fuel ramp on the intake manifold.)
  22. Refitting: Clean the injector wells on the intake manifold (holes into which the injectors are inserted) to ensure a tight seal.
  23. Avoid getting any debris into these holes, as they open almost directly into the valves. Any debris sucked into the engine can create catastrophic consequences.
  24. Improper installation of the injectors can cause an air leak, which can be very harmful!
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