Sierra, Silverado 2006-2007

Relieving Fuel System Pressure


A Schrader valve is provided on these fuel systems, in order to conveniently test or release the system pressure. A fuel pressure gauge and adapter will be necessary to connect the gauge to the fitting. Most of the MFI systems utilize a service valve on one end of the fuel rail assembly. The CMFI system covered here uses a valve located on the inlet pipe fitting, immediately before it enters the CMFI assembly (towards the rear of the engine)

  1. Before servicing the vehicle, refer to the Precautions section.
  3. Turn the ignition OFF .
  5. Disconnect the negative battery cable.
  7. Loosen the fuel filler cap in order to relieve the fuel tank vapor pressure.
  9. Connect a fuel pressure gauge to the fuel pressure valve/fitting.
  11. Wrap a shop towel around the fitting while connecting the gauge in order to avoid spillage.
  13. Install the bleed hose of the gauge into an approved container.
  15. Open the valve on the gauge to bleed the system pressure.

The fuel connections are now safe for servicing. Drain any fuel remaining in the gauge into an approved container.