Evaporative Emissions System: Testing and Inspection

Fig. 61 Testing purge control system:

SYSTEM TESTING

1. Disconnect the purge air hose from the air intake hose and plug the air intake hose.
2. Connect a hand vacuum pump to the disconnected purge air hose, Fig. 61.
3. While the engine is cold (coolant temperature less than 45 degrees C or 113 degrees F) verify that while the engine is held at 2,500 rpm it is possible to achieve 13 kPa (4 in. Hg) of steady vacuum.
4. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F) and verify that while the engine idles it is possible to achieve 13 kPa (4 in. Hg) of steady vacuum.
5. Accelerate the engine to 2,500 rpm and verify that vacuum leaks.

Overfill Limiter (Two Way Valve):

OVERFILL LIMITER VALVE

Remove the overfill limiter valve and blow gently through both ends. Air should pass through the valve in both directions with slight resistance.

Fig. 62 Testing purge control valve:

PURGE CONTROL VALVE

1. Remove the purge control valve.
2. Connect a hand vacuum pump to the vacuum nipple of the purge control valve, Fig. 62.
3. Apply 53 kPa (15 in. Hg) of vacuum and verify that the diaphragm chamber does not leak.
4. With no vacuum applied verify that air does not pass through the purge control valve.
5. Apply 27 kPa (8 in. Hg) of vacuum to the purge control valve and verify that air passes through the purge control valve.

Fig. 63 Testing purge control valve:

6. Connect the hand vacuum pump to the positive pressure nipple of the purge control valve, Fig. 63.
7. Apply a vacuum of 53 kPa (15 in. Hg) and verify that it does not leak.

Fig. 64 Testing the thermo valve:

THERMO VALVE

1. Disconnect the vacuum hoses from the thermo valve and connect a manual vacuum pump to the thermo valve, Fig. 64.
2. Apply a vacuum and verify that when engine coolant temperature is less than 50 degrees C or 122 degrees F that the thermo valve leaks.
3. Allow the engine to warm up until the coolant temperature exceeds 80 degrees C or 176 degrees F and verify that the thermo valve will hold a vacuum.

Note: If the thermo valve fails and must be replaced use 3M locking sealant 4171 or equivalent and torque the thermo valve to 20 to 40 Nm (15-30 ft. lbs.). Do not use wrenches or pliers on the resin part of the valve during installation.