GM Grand Am/Achieva/Calais/Skylark/Somerset 1985-98

Fuel Injectors

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REMOVAL & INSTALLATION



See Figures 1 and 2

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Fig. Fig. 1: Unfasten the retaining clip, then carefully remove the fuel injector from the fuel rail



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Fig. Fig. 2: After removing the injector from the fuel rail, remove and discard the O-ring seals

Use care in removing the fuel injectors to prevent damage to the electrical connector pins on the injector and the nozzle. 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 other components while removing the injector. Be sure to note that different injectors are calibrated for different flow rates. When ordering new fuel injectors, be sure to order the identical part number that is inscribed on the bottom of the old injector.

  1. Properly relieve fuel system pressure.
  2.  
  3. If not done already, disconnect the negative battery cable.
  4.  
  5. Detach the injector electrical connections.
  6.  
  7. If equipped, remove the intake manifold plenum (upper intake manifold).
  8.  
  9. Remove the fuel rail assembly. Refer to the appropriated procedure in this section for details.
  10.  
  11. Unfasten the injector retaining clip. Separate the injector from the fuel rail.
  12.  
  13. Remove the O-ring seals from the injector and discard. Save the O-ring backups for use during installation.
  14.  

To install:
  1. Make sure the O-ring backups are on the injectors prior to installing new O-rings. Prior to installing the injectors, coat the new injector O-ring seals with clean engine oil. Install the seals on the injector assembly.
  2.  
  3. Use new injector retainer clips on the injector assembly. Position the open end of the clip facing the injector electrical connector.
  4.  
  5. Install the injector into the fuel rail injector socket with the electrical connectors facing outward. Push the injector in firmly until it engages with the retainer clip locking it in place.
  6.  
  7. Install the fuel rail and injector assembly.
  8.  
  9. Attach the injector electrical connectors.
  10.  
  11. Install the intake manifold plenum if equipped.
  12.  
  13. Connect the negative battery cable. Turn the ignition to the ON position for two seconds, then turn it to the OFF position for ten seconds. Turn again to the ON position and check for fuel leaks.
  14.  

TESTING



The easiest way to test the operation of the fuel injectors is to listen for a clicking sound coming from the injectors while the engine is running. This is accomplished using a mechanic's stethoscope, or a long screwdriver. Place the end of the stethoscope or the screwdriver (tip end, not handle) onto the body of the injector. Place the ear pieces of the stethoscope in your ears, or if using a screwdriver, place your ear on top of the handle. An audible clicking noise should be heard; this is the solenoid operating. If the injector makes this noise, the injector driver circuit and computer are operating as designed. Continue testing all the injectors this way.


CAUTION
Be extremely careful while working on an operating engine, make sure you have no dangling jewelry, loose clothes, power tool cords or other items that might get caught in a moving part of the engine.All Injectors Clicking

If all the injectors are clicking, but you have determined that the fuel system is the cause of your driveability problem, continue diagnostics. Make sure that you have checked fuel pump pressure as outlined earlier in this section. An easy way to determine a weak or unproductive cylinder is a cylinder drop test. This is accomplished by removing one spark plug wire at a time, and seeing which cylinder causes the least difference in the idle. The one that causes the least change in idle speed is the weak cylinder.

If the injectors were all clicking and the ignition system is functioning properly, remove the injector of the suspect cylinder and bench test it. This is accomplished by checking for a spray pattern from the injector itself. Install a fuel supply line to the injector (or rail if the injector is left attached to the rail) and momentarily apply 12 volts DC and a ground to the injector itself; a visible fuel spray should appear. If no spray is achieved, replace the injector and check the running condition of the engine.

Injector Not Clicking See Figures 3, 4, 5 and 6

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Fig. Fig. 3: Unplug the fuel injector connector



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Fig. Fig. 4: Plug the correct "noid" light directly into the injector harness connector



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Fig. Fig. 5: If the correct "noid" light flashes while the engine is running, the injector driver circuit inside the PCM is working



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Fig. Fig. 6: Probe the two terminals of a fuel injector to check its resistance

If one or more injectors are found to be not operating, testing the injector driver circuit and computer can be accomplished using a "noid" light. First, with the engine not running and the ignition key in the OFF position, remove the connector from the injector you plan to test, then plug the "noid" light tool into the injector connector. Start the engine and the "noid" light should flash, signaling that the injector driver circuit is working. If the "noid" light flashes, but the injector does not click when plugged in, test the injector's resistance. resistance should be between 11-18 ohms.

If the "noid" light does not flash, the injector driver circuit is faulty. Disconnect the negative battery cable. Unplug the "noid" light from the injector connector and also unplug the PCM. Check the harness between the appropriate pins on the harness side of the PCM connector and the injector connector. Resistance should be less than 5.0 ohms; if not, repair the circuit. If resistance is within specifications, the injector driver inside the PCM is faulty and replacement of the PCM will be necessary.

 
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