GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide

Throttle Body Injection Unit

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Removal & Installation




CAUTION
Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well ventilated area. Do not allow fuel spray or vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.

It is recommended to replace all gaskets and O-rings on disconnected fuel system components. Read the procedure first to ensure that you will have the necessary parts to complete the repair.

  1. Disconnect the negative battery cable.
  2.  
  3. Properly relieve the fuel system pressure.
  4.  
  5. Remove the air cleaner.
  6.  
  7. Unplug the electrical connectors from the idle air control valve, throttle position sensor and fuel injectors.
  8.  
  9. Disengage the injector wiring harness from the throttle body.
  10.  
  11. Disconnect the throttle and the transmission control cables from the throttle body.
  12.  
  13. If equipped, disconnect the cruise control cable.
  14.  
  15. Remove the cables from the support bracket and/or remove the cable support bracket from the throttle body.
  16.  
  17. Label and disconnect the vacuum and PCV hoses from the throttle body.
  18.  
  19. Place a rag under the fuel line-to-throttle body connections (to catch any excess fuel), then disconnect the fuel lines from the throttle body.
  20.  

Use a back-up wrench on the TBI fuel nuts to prevent them from turning.

  1. Remove the fuel line O-rings and discard.
  2.  
  3. Remove the TBI attaching bolts and nuts and remove the TBI unit. Discard the gasket.
  4.  

See Figure 91095g13

Click image to see an enlarged view

Fig. Fig. 1: View of the TBI unit and mounting bolts

To install:
  1. Place a cloth in the intake manifold to prevent dirt from entering the engine.
  2.  
  3. Thoroughly clean the gasket mounting surfaces using a gasket scraper, if necessary. Remove the Cloth.
  4.  
  5. Position a new gasket onto the mounting flange. Install the throttle body and mounting bolts. Torque the throttle body-to-intake manifold nuts/bolts to 18 lbs. ft. (25 Nm).
  6.  
  7. Install new O-rings onto the fuel lines and connect them to the throttle body. Use a back-up wrench and tighten the nuts to 20 lbs. ft. (27 Nm).
  8.  
  9. Connect the vacuum hoses to the throttle body.
  10.  
  11. If removed, install the cable support bracket and tighten the screws to 88 lbs. in..
  12.  
  13. Install the throttle, transmission control and, if equipped, cruise control cables.
  14.  
  15. Plug in the electrical connectors to the idle air control valve, throttle position sensor and fuel injectors. Make sure all the connectors are fully seated and latched.
  16.  
  17. Connect the negative battery cable.
  18.  
  19. Turn the ignition switch to the ON position for 2 seconds then turn to the OFF position for 10 seconds. Again turn the switch to the ON position and check for leaks.
  20.  
  21. With the engine OFF , depress the accelerator pedal to the floor and release it. Ensure that the pedal returns freely.
  22.  
  23. Install the air cleaner assembly.
  24.  
  25. If necessary, reset the IAC valve pintle position as follows:
    1. Depress the accelerator pedal slightly.
    2.  
    3. Start and run the engine for 3 seconds.
    4.  
    5. Turn the ignition OFF for 10 seconds.
    6.  
    7. Restart the engine and check for proper idle operation,
    8.  

  26.  

 
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