Important: The fuel rail for the 5.3L regular production option (RPO) L59 (VIN Z) is compatible with fuel that has a composition of up to 85 percent Ethanol (E85). Because of this, the fuel rail will be serviced as an entire assembly that includes both left and right rail assemblies and the fuel return pipe.

1. Remove the engine sight shield. Refer to Upper Intake Manifold Sight Shield Replacement in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
2. Relieve the fuel system pressure. Refer to the Fuel Pressure Relief .
3. Disconnect the fuel feed (1) and fuel return (2) pipes from the fuel rail.



4. Remove the retaining clip attaching screw (4).
5. Remove the crossover fuel pipe retainer clip (5).
6. Remove the fuel return pipe attaching screw (3) and the fuel return pipe retainer (2).
7. Remove the fuel return pipe (1).
8. Remove and discard the fuel return pipe O-ring (6).

1. Lubricate a NEW fuel return pipe O-ring (6) with clean engine oil.
2. Install the fuel return pipe O-ring (6) onto the fuel return pipe (1).
3. Install the fuel return pipe (1).

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.

4. Install the fuel return pipe retainer (2) and the fuel return pipe attaching screw (3).
5. Install the crossover fuel pipe retainer clip (5).
6. Install the retaining clip attaching screw (4).

Tighten

•	Tighten the crossover fuel pipe retainer clip attaching screw (4) to 3.8 N·m (34 lb in).

•	Tighten the fuel return pipe attaching screw (3) to 5 N·m (44 lb in).




7. Connect the fuel return (2) and fuel feed (1) pipes to the fuel rail.
8. Tighten the fuel fill cap.
9. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
10. Use the following procedure in order to inspect for leaks:

10.1.

Turn ON the ignition, with the engine OFF, for 2 seconds.

10.2.

Turn OFF the ignition for 10 seconds.

10.3.

Turn ON the ignition, with the engine OFF.

10.4.

Inspect for fuel leaks.

11. Install the engine sight shield. Refer to Upper Intake Manifold Sight Shield Replacement in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
12. Install the fuel pressure connection cap.