Notice: 

An eight digit identification number is stamped on the left hand fuel rail (fueling even cylinders 2, 4, 6). Refer to this number if servicing or part replacement is required.

1. Relieve fuel system pressure. Refer to Fuel Pressure Relief .
2. Remove the upper intake manifold. Refer to Upper Intake Manifold Replacement in Engine Mechanical.
3. Disconnect the engine fuel feed pipe at the fuel rail.



4. Disconnect the engine fuel return pipe from the fuel pressure regulator.
5. Remove and discard the fuel feed pipe and fuel return pipe O-rings.
6. Disconnect the fuel injector harness main electrical connector.



7. Pull up the lock release of the fuel injector connector (2).



8. Depress the lock tab (1) and lift the connector from the injector.
9. Repeat the previous two steps in order to disconnect all of the fuel injector electrical connectors.
10. Remove the fuel injector wiring harness.



11. Disconnect the coolant temperature sensor electrical connector.



12. Remove the fuel rail bolts.
13. Remove the fuel rail with the fuel injectors.
14. Remove the injector O-ring seal from the spray tip end of each injector.
15. If you are replacing the fuel rail, remove the fuel injectors from the fuel rail. Refer to Fuel Injector Replacement in Engine Controls.

Caution: In order 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.

1. If you are replacing the fuel rail, install the fuel injectors to the fuel rail. Refer to Fuel Injector Replacement in Engine Controls.
2. Install the fuel injector O-rings using GM P/N 12345616, (Canadian P/N 993182) or the equivalent.
3. Carefully install the fuel rail with the fuel injectors to the lower intake manifold.
4. Ensure that the nozzle ends of each fuel injector are located properly in the injector bores.

Important: Do not press on the fuel pressure regulator valve when installing the fuel injector rail assembly.

5. Press on the injector rail using the palms of both hands until the fuel injectors are fully seated.

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.

6. Install the fuel rail bolts.

Tighten
Tighten the fuel rail attaching bolt to 10 N·m (89 lb in).




7. Connect the coolant temperature sensor electrical connector.
8. Install the injector electrical harness to the fuel rail.
9. Apply grease GM P/N 12377900 (Canadian P/N 10953529) or equivalent to the fuel injector electrical connectors.



10. Install the fuel injector electrical connectors to the fuel injectors.
11. Push the slide locks (2) into position.
12. Connect the fuel injector harness main electrical connector.
13. Install new O-rings to the fuel feed pipe and fuel return pipe.



14. Connect the fuel feed pipe to the fuel rail.

Tighten
Tighten the fuel feed pipe nut to 17 N·m (13  lb ft).




15. Connect the fuel return pipe to the fuel pressure regulator.

Tighten
Tighten the fuel return pipe nut to 17 N·m (13 lb ft).

16. Install the upper intake manifold. Refer to Upper Intake Manifold Replacement in Engine Mechanical.
17. Inspect for fuel leaks with the following procedure:

17.1.

Turn the ignition ON for 2 seconds.

17.2.

Turn the ignition OFF for 10 seconds.

17.3.

Turn the ignition ON.

17.4.

Inspect for fuel leaks.