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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1641 (Engine Control System & Fuel System - 4.3L - Troubleshooting And Diagnosis) >> Evaporative Emission System Diagnosis >> Flowmeter Test - Leak Detection

Flowmeter Test - Leak Detection

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Open the Nitrogen tank valve and turn the NITROGEN/SMOKE valve on the front control panel to NITROGEN.
  2. Connect the hose to the correct test orifice on the bottom front of the tester. For orifice size, refer to the GM Service manual for the vehicle being tested. The vehicle specific information can be found in service procedures for DTCs that relate to evaporative emission (EVAP) system leaks.
  3. Press and release the remote switch to activate the tester.
  4. Position the sliding red flag on the flowmeter to align with the floating indicator. When the red flag is set, press and release the remote switch to deactivate the tester.
  5. Remove the hose from the test orifice and install the hose onto the vehicle. For proper connection location, and the special tool numbers for any adapters that may be required, refer to the service procedures for DTCs that relate to EVAP system leaks.
  6. Ignition ON, seal the EVAP system per instructions in the service procedures for DTCs that relate to EVAP system leaks. Most systems can be sealed using a scan tool output control for the EVAP canister vent solenoid valve, other systems require that the vent system be plugged.
    7. NOTE:
    • Larger volume fuel tanks, and/or those with lower fuel levels, may require several minutes to fill with nitrogen.
    • Static buildup may cause the float indicator to stick. It may be necessary to tap on the flowmeter to free up the float.
  7. Press and release the remote switch to activate the nitrogen flow and fill the system.
  8. Compare the stable floating indicator position to the red flag.
    • ABOVE the red flag, the result is UNACCEPTABLE, FAIL-Go to Smoke Procedure
    • BELOW the red flag, the result is ACCEPTABLE, PASS-Test complete
  9. Press and release the remote switch to deactivate the tester.
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