Evaporative Emissions System: Testing and Inspection

Fig. 17 Testing The Purge Control System:

PURGE CONTROL SYSTEM INSPECTION

1. Disconnect the red striped vacuum hose from the throttle body, connect a hand vacuum pump to the hose and plug the nipple.
2. While the engine is cold (coolant temperature less than 40 degrees C or 104 degrees F) allow the engine to idle and apply 53 kPa or 15.3 in. Hg of vacuum and verify that vacuum holds.
3. Increase engine speed to 3,000 rpm, apply 53 kPa or 15.3 in. Hg of vacuum and verify that vacuum holds.
4. Allow the engine to warm up (engine coolant temperature greater than 80 degrees C or 176 degrees F).
5. With the engine operating at idle apply 53 kPa or 15.3 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 and apply 53 kPa Hg or 15.3 in. Hg and verify that vacuum is held momentarilly and then leaks.

Purge Port Vacuum Nipple:

PURGE PORT VACUUM SIGNAL INSPECTION

1. Warm up the engine (coolant temperature greater than 85 degrees C or 185 degrees C).
2. Disconnect the vacuum hose from purge nipple on the throttle body and connect a hand vacuum pump to the nipple.

Purge Control Vacuum vs Engine Speed:

3. Race the engine and verify that vacuum is constant. If no vacuum is present the vacuum port may be clogged.

Purge Control Solenoid Valve Inspection:

PURGE CONTROL SOLENOID VALVE INSPECTION

1. Disconnect the red striped vacuum hose from the purge control solenoid valve and connect a hand vacuum pump to the disconnected vacuum hose.
2. Disconnect the harness connector.
3. Apply vacuum and verify that vacuum is held.

Purge Control Solenoid Valve Inspection:

4. Apply 12vdc to the solenoid valve and verify that vacuum leaks.

Purge Control Solenoid Valve Inspection:

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