CTS 2003-2005

Fuel Injectors

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The fuel injectors used on these Sequential Multiport Fuel Injection (SFI) systems are solenoid operated devices controlled by the PCM. The PCM energizes the solenoid which opens a valve to allow fuel delivery. The fuel is injected under pressure in a cone-shaped spray pattern at the opening of the intake valve. Excess fuel not used by the injectors passes through the fuel pressure regulator before being returned to the fuel tank.

A fuel injector which is stuck partially open will cause a loss of fuel pressure after engine shut down, causing long crank times to be noticed on some engines. Excess fuel can also cause dilution of the engine lubricating oil.

The fuel injectors are mounted in components known as fuel rails. The injectors press into the fuel rail, are sealed by O-rings and secured by simple clips.



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Fig. Refer to the part number inscribed on the injector to make sure you get the correct part



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Fig. Another form of fuel injector identification



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Fig. Cross-section of a typical fuel injector



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Fig. Fuel injector components: upper O-ring (1), retaining clip (2), fuel injector body (3), back-up ring (4) and lower O-ring (5)

Use care when removing the fuel injectors to prevent damage to the electrical connector pins on the injector. The fuel injector is serviced as a complete assembly only and should not be immersed in any kind of cleaner. Support the fuel rail to avoid damaging any components while removing the injectors. Note too, that different injectors have different calibration, or flow rates. When ordering new fuel injectors, be sure to order the identical part number that is inscribed on the old injector.

On a sequential injected engine, as are all of the engines covered by the manual, it is most important not to mix up the injector connectors. The electrical connectors MUST be installed on the proper injector. Tag for identification all electrical connectors before detaching.

Removal & Installation



The fuel rail must be removed to service the fuel injectors.


CAUTION
To reduce the risk of fire and personal injury that may result from a fuel leak, always install the fuel injector O-rings in the proper position. If the upper and lower O-rings are different colors (black and brown), be sure to install the black O-ring in the upper position and the brown O-ring in the lower position on the fuel injector. The O-rings are the same size but are made of different materials. The fuel injector lower O-ring uses a nylon collar, called the O-ring Back-up, to properly position the O-ring on the fuel injector. Be sure to reinstall the O-ring back-up or the sealing O-ring may move out of position on the injector at installation. If the sealing O-ring is not seated properly, a vacuum leak is possible and driveability problems may occur.


NOTE
When servicing the fuel rail and injector assembly, precautions must be taken to prevent dirt and other contaminants from entering the fuel passages. It is recommended that all areas around fuel fittings be cleaned before disassembly and when disassembled, the fittings be capped and the holes plugged during servicing.

3.1L & 3.4L (VIN E & X) Engines


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Fig. Detach the fuel injector electrical connector



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Fig. The fuel injectors are usually retained to the fuel rail by a small clip



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Fig. With the retainer removed, the fuel injector can simply be pulled from the fuel rail



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Fig. Whenever any fuel system component that is sealed with an O-ring, including a fuel injector, is removed, the O-ring must be discarded and replaced with a new O-ring. The top O-ring is being removed here



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Fig. There is an O-ring and a nylon O-ring back-up piece used on the bottom of the injector. Discard the O-ring but retain the nylon O-ring back-up piece



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Fig. Retain the nylon O-ring back-up piece, but install new O-rings at assembly

  1. Disconnect the negative battery cable.
  2.  
  3. Relieve the fuel system pressure using the procedures found in this section.
  4.  
  5. Remove the fuel rail as outlined earlier in this section and place on a suitable workbench.
  6.  
  7. On a clean work surface, remove each injector O-ring seal from the spray tip end of each injector. Discard the seals. Fuel injector O-rings should always be replaced whenever fuel injectors are serviced. With the O-ring removed, the nylon O-ring back-up may slip off the injector. Be sure to retain the O-ring back-up for reuse
  8.  


WARNING
Use care when removing the fuel injectors to prevent damage to the small electrical connector pins or the fuel injection nozzles. Do not immerse the fuel injector in any type of cleaner. The fuel injector is an electrical component and may be damaged by this cleaning method. The fuel injector is serviced as a complete assembly only. If the fuel injectors are found to be leaking, the engine oil may be contaminated with fuel.

  1. Remove the fuel injector retaining clips and remove the injectors by simply pulling out of the fuel rail.
  2.  

To install:

  1. Clean all parts well. Fuel injector O-rings should always be replaced whenever the fuel injectors are serviced. Use the following procedure:
    1. Coat all O-rings with clean engine oil before installing.
    2.  
    3. Install the fuel injector nylon O-ring back-up ring first, then install the lower O-ring.
    4.  
    5. Install the fuel injector upper O-ring.
    6.  

  2.  
  3. Install the fuel injector to the fuel rail. When seated, install the retaining clip. Repeat for each injector that was removed.
  4.  
  5. Install the fuel rail with the injectors attached, as outlined earlier in this section.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Inspect for leaks using the following procedure:
    1. Turn the ignition switch to the ON position for 2 seconds.
    2.  
    3. Turn the ignition switch to the OFF position for 10 seconds.
    4.  
    5. Turn the ignition switch to the ON position again.
    6.  
    7. Inspect all areas for fuel leaks.
    8.  

  10.  

3.5L (VIN H) Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Relieve the fuel system pressure using the procedures found in this section.
  4.  
  5. Tag for identification and detach the electrical connectors from the fuel injectors.
  6.  
  7. Disconnect the fuel pressure regulator vacuum hose from the fuel pressure regulator.
  8.  
  9. Remove the PCV valve hose and the throttle body port hose.
  10.  
  11. Remove the wiring harness bolt and harness.
  12.  


NOTE
It may be necessary to remove the fuel rail from the intake manifold to allow increased fuel rail movement for fuel injector access.

  1. Release the fuel rail-to-intake manifold locking tab by pushing away toward the center of the intake manifold.
  2.  
  3. Remove the fuel injector up out of the intake manifold. GM recommends using tool J 43013 which is basically a small prying tool with a tapered end and a semi-circular cutout to accommodate the fuel injector. It is designed to fit between the bottom of the injector and the intake manifold, so the injector can be gently levered out of the lower intake manifold. Use care if using substitutes.
  4.  


NOTE
It may be necessary to release the adjacent injectors from the intake manifold to allow increased fuel rail movement for injector access.

  1. Spread the injector retainer clip to release the injector from the fuel rail. Remove and discard the O-rings. They must be replaced with new seals.
  2.  

To install:


CAUTION
To reduce the risk of fire and personal injury that may result from a fuel leak, always install the fuel injector O-rings in the proper position. If the upper and lower O-ring are different colors (black and brown), be sure to install the black O-rings in the upper position and the brown O-ring in the lower position on the fuel injector. The O-rings are the same size but are made of different materials. The fuel injector O-rings should always be replaced whenever fuel injectors are serviced.

  1. Lubricate the new upper and lower O-rings with clean engine oil.
  2.  
  3. Install the new upper and lower O-rings on the fuel injector.
  4.  
  5. Install the fuel injector(s) onto the fuel rail. Make sure the injectors are aligned properly with the electrical connector in the correct orientation. Push in the retainer clip(s) far enough to engage the retainer clip with the machined slots on the rail socket.
  6.  
  7. Snap the fuel rail down onto the intake manifold.
  8.  
  9. Connect the fuel injector harness to the injectors using care to get the connectors on their proper injector. Install the wiring harness hold down bolt.
  10.  
  11. Connect the throttle body, PCV hose and fuel pressure regulator vacuum hoses.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Inspect for leaks using the following procedure:
    1. Turn the ignition switch to the ON position for 2 seconds.
    2.  
    3. Turn the ignition switch to the OFF position for 10 seconds.
    4.  
    5. Turn the ignition switch to the ON position again.
    6.  
    7. Inspect all areas for fuel leaks.
    8.  

  16.  

3.8L (VIN 1) Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the cosmetic/acoustic engine cover.
  4.  
  5. Relieve the fuel system pressure using the procedures found in this section.
  6.  
  7. Clean the fuel rail assembly and connections.
  8.  
  9. Remove the fuel rail, as outlined earlier in this section.
  10.  
  11. On a clean work surface, remove each injector O-ring seal from the spray tip end of each injector. Discard the seals. Fuel injector O-rings should always be replaced whenever fuel injectors are serviced. With the O-ring removed, the nylon O-ring back-up may slip off the injector. Be sure to retain the O-ring back-up for reuse
  12.  
  13. Use care when removing the fuel injectors to prevent damage to the small electrical connector pins or the fuel injection nozzles. Do not immerse the fuel injector in any type of cleaner. The fuel injector is an electrical component and may be damaged by this cleaning method. The fuel injector is serviced as a complete assembly only. If the fuel injectors are found to be leaking, the engine oil may be contaminated with fuel.
  14.  
  15. Remove the fuel injector retaining clips and remove the injectors by simply pulling out of the fuel rail.
  16.  

To install:

  1. Clean all parts well. Fuel injector O-rings should always be replaced whenever the fuel injectors are serviced. Use the following procedure:
    1. Coat all O-rings with clean engine oil before installing.
    2.  
    3. Install the fuel injector nylon O-ring back-up ring first, then install the lower O-ring (brown).
    4.  
    5. Install the fuel injector upper O-ring (black).
    6.  

  2.  
  3. Install the fuel injectors to the fuel rail.
  4.  
  5. Assemble the fuel rail with the fuel injectors to the lower intake manifold. Seat the fuel injectors by hand. Install the fuel rail, as outlined earlier in this section.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Inspect for leaks using the following procedure:
    1. Turn the ignition switch to the ON position for 2 seconds.
    2.  
    3. Turn the ignition switch to the OFF position for 10 seconds.
    4.  
    5. Turn the ignition switch to the ON position again.
    6.  
    7. Inspect all areas for fuel leaks.
    8.  

  10.  

3.8L (VIN K) Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the cosmetic/acoustic engine cover.
  4.  
  5. Relieve the fuel system pressure using the procedures found in this section.
  6.  
  7. Clean the fuel rail assembly and connections.
  8.  
  9. Remove the fuel rail as outlined earlier in this section.
  10.  
  11. On a clean work surface, remove each injector O-ring seal from the spray tip end of each injector. Discard the seals. Fuel injector O-rings should always be replaced whenever fuel injectors are serviced. With the O-ring removed, the nylon O-ring back-up may slip off the injector. Be sure to retain the O-ring back-up for reuse
  12.  
  13. Use care when removing the fuel injectors to prevent damage to the small electrical connector pins or the fuel injection nozzles. Do not immerse the fuel injector in any type of cleaner. The fuel injector is an electrical component and may be damaged by this cleaning method. The fuel injector is serviced as a complete assembly only. If the fuel injectors are found to be leaking, the engine oil may be contaminated with fuel.
  14.  
  15. Remove the fuel injector retaining clips and remove the injectors by simply pulling out of the fuel rail.
  16.  

To install:

  1. Clean all parts well. Fuel injector O-rings should always be replaced whenever the fuel injectors are serviced. Use the following procedure:
    1. Coat all O-rings with clean engine oil before installing.
    2.  
    3. Install the fuel injector nylon O-ring back-up ring first, then install the lower O-ring (brown).
    4.  
    5. Install the fuel injector upper O-ring (black).
    6.  

  2.  
  3. Install the fuel injectors to the fuel rail.
  4.  
  5. Assemble the fuel rail with the fuel injectors to the lower intake manifold. Seat the fuel injectors by hand. Install the fuel rail as outline earlier in this section.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Inspect for leaks using the following procedure:
    1. Turn the ignition switch to the ON position for 2 seconds.
    2.  
    3. Turn the ignition switch to the OFF position for 10 seconds.
    4.  
    5. Turn the ignition switch to the ON position again.
    6.  
    7. Inspect all areas for fuel leaks.
    8.  

  10.  

Testing



The injectors can be tested by installing a "noid light," (a headlamp bulb may work) into the injector electrical connector, which confirms voltage when the light flashes.

  1. Start the engine and listen to each fuel injector individually for a clicking sound.
  2.  
  3. Turn the engine OFF and detach the electrical connector from the injector(s) that did not have a clicking sound.
  4.  
  5. Check the injector for continuity across the terminals. Compare the resistance value to a known good injector. The readings should be similar, if so proceed to the next step. If readings differ greatly, replace the injector.
  6.  



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Fig. Detach the fuel injector electrical connector . . .



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Fig. . . . then use an ohmmeter to check injector resistance. Compare with specifications from a known good injector

  1. Check between each injector terminal and ground. If continuity exists, replace the injector.
  2.  
  3. Detach the fuel injector connector and connect a noid light to the wiring harness connector. Crank the engine, while watching the light. Perform this test on at least two injectors before proceeding. If the light does not flash, check the injector power supply and ground control circuitry. If the light flashes proceed to the next step.
  4.  
  5. If the light flashes, remove the fuel rail from the engine and following the procedure below check the injector operation:
    1. Using mechanic's wire, secure the injector to the fuel rail.
    2.  
    3. Place a clear plastic container around each injector.
    4.  

  6.  


CAUTION
Prior to performing this test, all fuel safety precautions must be followed. Make certain the container is approved to handle fuel and is securely positioned around the injector. Do NOT use a glass container. Glass containers can be easily damaged, resulting in a serious fire hazard.

  1. With the help of an assistant or using a remote starter button, crank the engine for 15 seconds while observing the injector operation. The injector should produce a cone shaped spray pattern and all containers should retain equal amounts of fuel.
  2.  
  3. Once the cranking test is complete, leave the fuel rail pressurized and observe the injectors for leakage.
  4.  

  1. Replace any injector which is leaking or fails to provide a cone shaped spray pattern when energized.
  2.  

 
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