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    1963 Cadillac Deville 6.4L 4BL 8cyl

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    1720 S RIDGEWOOD A
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    GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

    Fuel Injector(s)

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    The fuel injector is a solenoid device controlled by the PCM that meters pressurized fuel to a single cylinder. When the PCM energizes the injector coil, a normally closed bail valve opens, allowing fuel to flow past a director plate to the injector outlet. The director plate has holes that control the fuel flow, generating a dual conical spray pattern of finely atomized fuel at the injector outlet. Fuel from the outlet is directed at both intake valves, causing it to become further vaporized before entering the combustion chamber.

    Fuel injectors will cause various driveability conditions if they will not open, are stuck open, leaking or have a low coil resistance.

    Fuel system deposits can cause various driveability problems. Deposits usually occur during hot soaks. Poor fuel quality or driving patterns such as short trips followed by long cool down periods can cause injector deposits. This occurs when the fuel remaining in the injector tip evaporates and leaves deposits. Leaking injectors can increase injector deposits. Deposits on fuel injectors affect their spray pattern, which in turn could cause reduced power, unstable idle, hard starts, and poor fuel economy.



    Click image to see an enlarged view

    Fig. A typical ported fuel injector with its two O-rings and retaining clip



    Click image to see an enlarged view

    Fig. A schematic of a typical ported fuel injector

    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, extremely 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 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.

    One or More Injectors Are Not Clicking


    Click image to see an enlarged view

    Fig. Unplug the fuel injector connector



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



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



    Click image to see an enlarged view

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

    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.

    REMOVAL & INSTALLATION



    3.0L Engine

    NOTE
    Use care in removing the fuel rail assembly to prevent damage to the injector electrical connector terminals and the injector spray tips. When removed, support the rail to avoid damaging its components.


    NOTE
    Prevent dirt and other contaminants from entering open lines and passages. Fittings should be capped, and holes plugged, during servicing.

    1. Disconnect the negative battery cable.
    2.  
    3. Properly relieve the fuel system pressure.
    4.  
    5. Remove the intake plenum.
    6.  


    NOTE
    Mask the intake ducts-entry of foreign objects can cause severe engine damage.

    1. Loosen the fuel rail bracket volts near the fuel supply/return lines.
    2.  
    3. Disconnect the fuel rail intermediate lines (supply/lines) and position away from the fuel rail.
    4.  
    5. Detach the fuel injector electrical connectors and unclip harness from the fuel rail.
    6.  
    7. Disconnect the fuel rail attaching bolts from the intake manifold.
    8.  
    9. Disconnect the fuel pressure regulator vacuum line.
    10.  


    CAUTION
    Safety glasses must be worn when using compressed air, as flying dirt particles may cause eye injury.

    1. Using compressed air, blow dirt out of area where injectors enter intake casting.
    2.  
    3. Release the locking tabs on the fuel rail and pry each injector out of intake manifold.
    4.  
    5. Remove the fuel rail assembly.
    6.  
    7. Remove the injectors from the fuel rail.
    8.  
    9. Remove the O-rings from the injectors. Discard the O-rings.
    10.  


    NOTE
    If it is necessary to remove rust or burrs from the fuel line, use emery cloth in a radial motion with the line end to prevent damage to the O-ring sealing surface.



    Using a clean shop towel, wipe off the male line end.
     
    Inspect both ends of the fitting for dirt and burr. 'Clean or replace the components/assemblies as required.
     

    To install:

    1. Lubricate the new injector O-rings with clean engine oil and install on the injectors.
    2.  
    3. Install the injectors to the fuel rail with the new retainer clips.
      1. Ensure the injectors are aligned by orienting the electrical connector perpendicular to the crankshaft centerline.
      2.  

    4.  
    5. Install the fuel rail with injectors to intake manifold.
    6.  
    7. Reconnect the fuel pressure regulator vacuum line.
    8.  
    9. Reconnect the fuel rail attaching bolts to the intake manifold.
    10.  
    11. Reattach the fuel injector electrical connectors and clip harness to fuel rail.
    12.  
    13. Reconnect the fuel rail intermediate lines (supply-return) to the fuel rail.
    14.  
    15. Tighten the fuel fittings to the fuel rail.
      1. Apply a few drops of clean engine oil to the male ends of the engine fuel rail inlet and outlet tubes.
      2.  

    16.  
    17. Install/tighten the fuel rail bracket bolts near the fuel supply-return lines.
    18.  
    19. Reinstall the intake plenum.
    20.  
    21. Disconnect the negative battery cable.
    22.  
    23. Crank the engine for a few seconds (if the engine starts, turn it off) and then check for fuel leaks.
    24.  

    4.5L and 4.9L Engines
    1. Disconnect the negative battery cable.
    2.  
    3. Properly relieve the fuel system pressure.
    4.  
    5. Raise the hood, install fender covers, and remove the air cleaner assembly.
    6.  
    7. Remove the fuel rail assembly. With the fuel rail inverted, detach the electrical connector to each injector by pushing in on the connector clip while pulling the connector body away from the injector. Spread open the clip slightly and slide the clip away from the fuel rail.
    8.  
    9. Remove the injector by twisting back and forth.
    10.  
    11. Disassemble the injector O-ring seals from the injector and discard.
    12.  

    To install:

    1. Lubricate the new injector O-ring seals with petroleum based grease and install it on the injector assembly.
    2.  
    3. Install a new injector clip on the injector assembly.
    4.  
    5. Install the fuel injector assembly into the fuel rail socket as follows:
      1. Push in to engage the retainer clip with the fuel rail cup.
      2.  
      3. The electrical connectors should be facing the engine front for injectors 1 through 4. The electrical connectors should be facing the engine rear for injectors 5 through 8.
      4.  

    6.  
    7. Attach the electrical connector to the injector assembly.
    8.  
    9. Install the fuel rail assembly.
    10.  
    11. Energize the fuel pump and check for leaks.
    12.  
    13. Perform the Idle Learn procedure.
    14.  



    Click image to see an enlarged view

    Fig. Injector assembly and retainer-4.5L and 4.9L engines



    Click image to see an enlarged view

    Fig. Installing the injector assembly-4.5L and 4.9L engines

    4.6L Engine
    1. Remove the fuel pump relay in the engine compartment micro relay center.
    2.  
    3. Relieve the fuel system pressure.
    4.  
    5. Remove the intake manifold top cover.
    6.  
    7. Detach the 2 intake manifold electrical connectors.
    8.  
    9. Remove the fuel rail along with the injectors out of the intake manifold.
    10.  
    11. Remove the injectors from the fuel rail.
    12.  



    Click image to see an enlarged view

    Fig. Unplug the injector harness from the injector



    Click image to see an enlarged view

    Fig. Using a small pry tool, pry the injector lock from the injector



    Click image to see an enlarged view

    Fig. Gently pull the injector from the rail. A slight twisting motion may help ease removal

    To install:

    1. Install the injectors to the fuel rail.
    2.  
    3. Install the fuel rail along with the injectors into the intake manifold housing.
    4.  
    5. Install the intake manifold top cover and tighten the retaining bolts to 106 inch lbs. (12 Nm).
    6.  
    7. Attach the 2 intake manifold electrical connectors.
    8.  
    9. Install the fuel pump relay in the engine compartment micro relay center.
    10.  

    TESTING



    The Injector Flow/Voltage Drop Check compares the fuel pressure drop when each injector is pulsed for a set amount of time. Since each injector is pulsed the same, the fuel pressure drop for each injector is pulsed the same, the fuel pressure drop for each injector should be approximately the same. Suspect fuel injectors can be identified by either too high or too low fuel pressure drop. This check also determines if the voltage drop of the injector is within specification. Injector voltage drop out of specification can cause driveability conditions that are intermittent or that do not show up during an injector flow check. This chart requires special tools J 34730-91 Fuel pressure gauge, J 39200 Voltmeter, J39021 Fuel injector tester.



    Click image to see an enlarged view

    Fig. Use an ohmmeter check injector resistance. Compare readings with a known good injector

    The injector circuit can be can be tested by installing a "noid light," into the injector electrical harness connector. The light confirms a voltage feed when it flashes, as though the injector was firing.

    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 that did not have a clicking sound.
    4.  
    5. Check the injector for continuity across the terminals. Compare the injector the resistance value to a known good injector. The readings should be similar, if so proceed to the next test. If readings differ greatly, replace the injector.
    6.  
    7. Check between each injector terminal and ground. If continuity exists, replace the injector.
    8.  
    9. Detach the fuel injector connector and attach a noid light to the wiring harness connector. Crank the engine, while observing 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.
    10.  
    11. If the light flashes remove the fuel rail from the engine and following the procedure given, 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.  

    12.  


    CAUTION
    Before performing this test, all fuel safety precaution 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 contain 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 that leaks or fails to provide a good spray pattern.
    2.  

     
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