GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 41413 EVAP Pressure/Purge Diagnostic Station

Inspection Procedure

Notice: Use the EVAP Pressure/Purge Diagnostic Station J 41413 in order to provide a clean, dry, low pressure gas source. Do not substitute any other pressurized gas source. Damage may result to the EVAP system.

Important: Do not perform this procedure unless instructed by an EVAP diagnostic.

  1. Turn OFF the ignition.
  2. Remove the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
  3. Lightly tap the EVAP canister purge valve on a clean hard surface.
  4. Inspect for carbon particles exiting either of the vacuum ports.
  5. • If no carbon particles are found reinstall the EVAP canister purge valve and continue with the EVAP cleaning procedure.
    • If carbon particles are found during the inspection procedure, replace the EVAP canister purge valve and continue with the EVAP cleaning procedure. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
    • If you were instructed to replace the EVAP canister purge valve, and no carbon particles are found, return to the EVAP diagnostic procedure. Do not perform the EVAP cleaning procedure.

EVAP Cleaning Procedure

  1. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement .
  2. Turn OFF the main valve on the J 41413 .
  3. Disconnect the hose from the diagnostic station pressure regulator.
  4. Using a section of vacuum hose, connect one end to the diagnostic station pressure regulator.
  5. Connect the other end of the vacuum hose to the canister side of the EVAP purge pipe.
  6. Turn ON the main nitrogen cylinder valve and continue to discharge nitrogen for 15 seconds.
  7. If the EVAP purge pipe is plugged and the nitrogen does not dislodge the carbon particles, replace the EVAP purge pipe. Refer to Evaporative Emission Hoses/Pipes Replacement - Engine/Chassis .
  8. Return the EVAP Pressure/Purge Diagnostic Station to the EVAP Pressure/Purge Diagnostic Stations original condition.
  9. Install a new EVAP canister. Refer to Evaporative Emission Canister Replacement .
  10. Lower the vehicle.
  11. Continue with the published service manual diagnostic DTC procedure.