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: Proceed with the following procedure only if referenced by a EVAP diagnostic or repair procedure.

  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 hard surface.
  4. Inspect for carbon particles exiting either of the vacuum ports.
  5. • If no carbon particles were detected, but a blockage was detected during a diagnostic procedure. Install the original EVAP canister purge valve and continue with the cleaning procedure.
    • If carbon particles are found during the inspection procedure, continue with the cleaning procedure.
    • If a diagnostic procedure directed you to replace the EVAP canister purge valve and no carbon particles were detected. Replace the EVAP canister purge valve and return to the published service procedure.

Cleaning Procedure

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement .
  3. Turn OFF the main valve on the J 41413 .
  4. Disconnect the hose from the diagnostic station pressure regulator.
  5. Using a section of vacuum hose, connect one end onto the diagnostic station pressure regulator.
  6. Connect the other end of the vacuum hose to the canister side of the purge pipe.
  7. Turn ON the main nitrogen cylinder valve and continue to discharge nitrogen for 15 seconds.
  8. If the nitrogen does not dislodge the carbon particles, replace the purge pipe. Refer to Evaporative Emission Hoses/Pipes Replacement - Chassis/Canister .
  9. Return the EVAP pressure/purge diagnostic station to the stations original condition.
  10. Install a new EVAP canister. Refer to Evaporative Emission Canister Replacement .
  11. Lower the vehicle.
  12. Install a new EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
  13. Return to the published service procedure.