Evaporative Emissions System: Testing and Inspection

Fig. 27 Testing The Purge Control Valve:

PURGE CONTROL VALVE INSPECTION

1. Remove the purge control valve from the vehicle.
2. Connect a hand vacuum pump to the vacuum nipple of the purge control valve.
3. With no vacuum applied to the purge control valve verify that air will not pass through the purge control valve.
4. Apply 1.4 in. Hg of vacuum and verify that air will pass through the purge control valve.

Fig. 30 Testing The Thermo Valve:

THERMO VALVE INSPECTION

1. Mark and then disconnect the vacuum hoses from the thermo valve and connect a hand vacuum pump.
2. While engine coolant temperature is less than 60 degrees C or 140 degrees F attempt to apply vacuum to port "C" and verify that vacuum leaks.
3. Warm up engine until coolant temperature exceeds 70 degrees C or 158 degrees F.
4. Apply vacuum and verify that vacuum holds.

Fig. 25 Testing The Bowl Vent Valve:

BOWL VENT VALVE INSPECTION

1. Allow the engine to cool off completely to prevent fuel from gushing out of the BVV nipple.
2. Remove the air cleaner.
3. Disconnect the bowl vapor hose from the bowl vent valve (BVV) nipple and connect a hand vacuum pump to the BVV nipple.
4. Apply 20 kPa or 3 in. Hg of vacuum to the BVV and verify that when the engine is running vacuum holds and that when the engine is off vacuum leaks.