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Home >> GMC >> 1999 >> Forward Control 7.4 J >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Engine Controls - Removal & Installation) >> Emission Systems & Sub-Systems >> EVAP System Cleaning >> Cleaning Procedure
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Cleaning Procedure

WARNING: This page is about a different car, the 2003 Pontiac Bonneville, 2003 Buick Park Avenue, and 2003 Buick LeSabre. However, it is still accessible from the selected car via links, so may be relevant.
  1. Raise and support vehicle. Remove the EVAP canister. See EVAP CANISTER . Turn off the main valve on the EVAP Pressure/Purge Diagnostic Station (J-41413).
  2. Disconnect the hose from the diagnostic station pressure regulator. Using a section of vacuum hose, connect one end onto the diagnostic station pressure regulator. Connect the other end of the vacuum hose to the canister side of the purge pipe.
  3. Turn on the main nitrogen cylinder valve and continue to discharge nitrogen for 15 seconds. If the nitrogen does not dislodge the carbon particles, replace the purge pipe. Return the EVAP pressure/purge diagnostic station to the stations original condition.
  4. Install a new EVAP canister. Lower the vehicle. Install a new EVAP canister purge valve. Return to the diagnostic procedure that sent you here.
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