GM Service Manual Online
For 1990-2009 cars only

Inspection Procedure

Tool Required

J 41413 EVAP pressure/purge diagnostic station


    Object Number: 20803  Size: SH

    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: Whenever the EVAP DTC diagnostics lead to a no trouble found or an EVAP purge solenoid replacement, proceed with the following EVAP canister diagnostics.

  1. Remove the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
  2. Lightly tap the EVAP purge solenoid on a clean work area.
  3. Look for carbon particles or carbon dust exiting from either of the vacuum ports.
  4. • Reinstall the purge solenoid If no carbon release is evident. Continue with the published service manual DTC procedures.
    • Continue with this service procedure if carbon is released from the purge solenoid.
  5. Remove the EVAP canister from the vehicle. Refer to Evaporative Emission Canister Replacement .
  6. Turn OFF the main cylinder valve (1) on the J 41413 EVAP pressure/purge diagnostic station.
  7. Disconnect the black hose (4) that connects the nitrogen cylinder to the cart J 41413 at the pressure regulator (5) by unscrewing the knurled nut on the pressure regulator.
  8. Connect a section of the vacuum hose to the open fitting of the J 41413 pressure regulator (5).
  9. Connect the other end of the vacuum hose to the engine compartment EVAP purge pipe.
  10. Turn ON the main nitrogen cylinder valve (1).
  11. Continue to blow any debris from the purge pipe for 15 seconds.
  12. Return the J 41413 to its original condition by re-installing the black hose (4) disconnected in step 6.
  13. Replace the EVAP canister purge solenoid valve with the new component. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
  14. Replace the EVAP canister with the new component. Refer to Evaporative Emission Canister Replacement .

  15. Object Number: 21046  Size: SH
  16. Connect the J 41413 to the vehicle EVAP service port.
  17. Turn the 4-position switch to Purge.
  18. Idle the engine at the normal operating temperature.
  19. Open the throttle until the engine speed reaches 2,000 RPM.
  20. Observe the H2O vacuum gauge on the EVAP cart. The vacuum should read more than 15 in. H2O.
  21. • Inspect the vacuum supply to the EVAP purge solenoid valve if the vacuum is less than 15 in. H2O.
    • Continue with the published service diagnostics if the vacuum is more than 15 in. H2O.