GM Service Manual Online
For 1990-2009 cars only

Disassembly Procedure

  1. Remove the throttle body injection (TBI) unit from the engine. Refer to Throttle Body Assembly Replacement .
  2. Important: Do not remove the fuel pressure regulator valve from the TBI unit. The fuel pressure regulator valve is calibrated at the factory and is not adjustable. The fuel pressure regulator valve is not serviceable separate from the TBI upper assembly.


    Object Number: 159161  Size: SH
  3. Remove the two bolts and the air cleaner bracket from the TBI unit.

  4. Object Number: 581522  Size: SH
  5. Remove the 2 screws (1) and the wire harness cover plate (2) from the TBI unit.

  6. Object Number: 581519  Size: SH
  7. Remove the 2 screws (1) and the fuel injector cover (2) with the electrical leads attached from the fuel injector.

  8. Object Number: 581547  Size: SH
  9. Remove the two screws (2) and the fuel injector electrical connector (1) from the TBI unit.
  10. Release the lock tab on the electrical terminal of each fuel injector wire lead, and remove both leads from the electrical connector (1).

  11. Object Number: 581621  Size: SH
  12. Guide the fuel injector wire leads (1) thru the electrical connector passage (2) of the throttle body.

  13. Object Number: 55774  Size: SH
  14. Remove the fuel injector from the TBI unit.
  15. Remove the two screws and the throttle position (TP) sensor from the TBI unit.

  16. Object Number: 159165  Size: SH
  17. Remove the 2 screws from the upper section and the lower section of the TBI unit.
  18. Separate the upper (1) and the lower (2) sections of the TBI unit.

Assembly Procedure


    Object Number: 55780  Size: SH
  1. Install a new gasket (1) onto the TBI lower assembly (2).

  2. Object Number: 159165  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the upper TBI assembly (1) to the lower TBI assembly (2), and secure the assembly with the 2 screws.
  4. Tighten
    Tighten the TBI unit attaching screws to 3.5 N·m (31 lb in).

  5. Connect the TP sensor to the TBI unit.
  6. Loosely install the TP sensor to the TBI unit with the 2 screws.

  7. Object Number: 581621  Size: SH
  8. Guide the fuel injector wire leads (1) thru the electrical connector passage (2) of the throttle body.

  9. Object Number: 581625  Size: SH
  10. Insert each terminal of the wire lead into the electrical connector. Correctly align the terminals (2) so that the terminals will lock into place. The polarity of the terminals is not important.

  11. Object Number: 581547  Size: SH
  12. Gently pull the wire leads back thru the connector passage, guiding the electrical connector into the housing.
  13. Install the electrical connector (1) to the TBI unit, and secure the connector with the 2 screws (2).

  14. Object Number: 165570  Size: SH
  15. Install a new lower injector insulator into the fuel injector cavity of the TBI unit.
  16. Notice: Do not twist the fuel injector during the installation to the throttle body in order to prevent damage and misalignment of the fuel injector O-ring seals.

  17. Install the fuel injector to the TBI unit.

  18. Object Number: 581519  Size: SH
  19. Install the fuel injector cover (2) with the electrical leads attached to the fuel injector, and secure the cover with the 2 screws (1).

  20. Object Number: 581522  Size: SH
  21. Install the wire harness cover plate (1). Be careful not to pinch any of the wire leads.

  22. Object Number: 159161  Size: SH
  23. Install the air cleaner bracket to the TBI unit, and secure the bracket with the 2 bolts.
  24. Tighten
    Tighten the ACL bracket bolt to 10 N·m (89 lb in).

  25. Install the TBI unit onto the engine. Refer to Throttle Body Assembly Replacement .
  26. Adjust the TP sensor. Refer to Throttle Position Sensor Adjustment .