Fuel Rail: Service and Repair

Model R620 Fuel Rail Assembly:

REMOVAL
Before removal, the fuel rail assembly may be cleaned with a spray type engine cleaner, GM X-30A or equivalent, following package instructions. Do not soak fuel rails in liquid cleaning solvent.

1. Disconnect the negative battery terminal.
2. Relieve the fuel system pressure. Refer to Fuel Delivery and Air Induction / Service and Repair.
3. Remove the intake manifold plenum.
4. Remove the fuel line bracket bolt and disconnect the fuel lines at rail. [1]
5. Remove the fuel inlet and the return line O-rings (1,2), and discard.
6. Disconnect the vacuum line at pressure regulator.
7. Disconnect the injector electrical connectors.
8. Remove the rail retaining bolts and fuel rail assembly.

CAUTION:
^ Use care in removing the fuel rail assembly, to prevent damage to the injector electrical connector terminals and the injector spray tips.
^ Prevent dirt and other contaminants from entering open lines and passages. All fittings should be capped, and holes plugged, during servicing.

Injectors
^ Remove the injector O-ring seal from spray tip end of each injector and discard seals.
^ Before installing the injectors in fuel rail, lubricate the new injector O-ring seals with engine oil then install on spray tip end of each injector.

INSTALLATION
1. Install the fuel rail assembly in the intake manifold. Tilt the rail assembly to install the injectors.
2. Install the fuel rail attaching bolts and torque to 10 Nm (88 lb in)
3. Connect the injector electrical connectors.
4. Connect the vacuum line to the pressure regulator.
5. Install the new O-rings on the fuel lines.
6. Connect the fuel feed and return lines [1] and torque to
23 Nm (17 lb ft).

Inspection
^ Temporarily connect the negative battery terminal.
^ Turn the ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten seconds. Again turn to the "ON" position and check for fuel leaks.
^ Disconnect the negative battery terminal.

7. Install the intake manifold plenum.
8. Tighten the fuel filler cap.
9. Connect the negative battery terminal.

[1] Use a back-up wrench on the fuel rail fittings to prevent them from turning.

NOTE: The Electronic Control Module (ECM) will need to relearn the Idle Air Control (IAC) valve pintle position following battery reconnection. This procedure allows the ECM memory to be updated and provides for a stable idle speed.

Idle Learn Procedure
1. Install the Tech 1 "SCAN" tool.
2. Ignition "ON" engine "OFF".
3. Select the "IAC SYSTEM", then "IDLE LEARN" in the "MISC. TEST" mode.
4. Proceed with the idle learn as directed by the Tech 1 "SCAN" tool.