Evaporative Emissions System: Testing and Inspection

Fig. 12 Testing The Purge Control System:

PURGE CONTROL SYSTEM INSPECTION

1. Disconnect the red striped vacuum hose from the throttle body and connect a hand vacuum pump to the hose and plug the nipple.
2. While the engine is cold (coolant temperature less than 60 degrees C or 140 degrees F) allow the engine to idle and apply 50 kPa or 14 in. Hg of vacuum and verify that vacuum holds.
3. Increase engine speed to 3,000 rpm, apply 50 kPa Hg or 14 in. Hg of vacuum and verify that vacuum holds.
4. Allow the engine to warm up (engine coolant temperature greater than 70 degrees C or 158 degrees F).
5. With the engine operating at idle apply 50 kPa Hg or 14 in. Hg of vacuum and verify that vacuum holds.
6. Within three minutes of engine start increase engine speed to 3,000 rpm. Attempt to apply vacuum and verify that vacuum leaks.
7. After more than three minutes have elapsed since engine start increase engine speed to 3,000 rpm, apply 50 kPa Hg or 14 in. Hg and verify that vacuum is held momentarilly and then leaks. (Note! Vacuum will leak continously if the test is being performed at elevations greater than 2,200 m (7,200 ft.) or intake air temperature is greater than 50 degrees C or 122 degrees F.

Fig. 16 Component Locations (Purge Hose Vacuum Nipple):

PURGE PORT VACUUM INSPECTION

1. Warm up the engine until coolant temperature exceeds 85 degrees C or 185 degrees F.
2. Disconnect the vacuum hose from the throttle body purge hose nipple and connect a hand vacuum pump to the nipple.

Fig. 18 Purge Control Vacuum vs Engine RPM:

3. Start the engine and verify that vacuum is present at the purge port and does not vary with engine rpm. If no vacuum is present the port may be clogged.

Fig. 21 Connecting A Vacuum Pump To The Purge Control Solenoid Valve:

PURGE CONTROL SOLENOID VALVE INSPECTION

1. Mark and then disconnect the vacuum hoses (black, red striped) from the solenoid valve.
2. Disconnect the harness connector from the solenoid valve.
3. Connect a hand vacuum pump to the nipple the red striped hose was removed from.

Fig. 22 Testing Operation Purge Control Solenoid Valve:

4. Apply vacuum to the solenoid valve and verify that when power is applied vacuum leaks and when power is removed vacuum holds.







5. Measure the solenoid coil resistance and verify that it is between 36 and 44 ohms at 20 degrees C or 68 degrees F.