Evaporative Emissions System: Testing and Inspection

PURGE CONTROL SYSTEM TEST

NOTE: When disconnecting the vacuum hoses, make an identifying mark on them to ensure proper routing when reconnecting.

Purge Control System Test:

COLD ENGINE TEST - Coolant temperature below 60°C (140°F)
1. Disconnect the air purge hose from the air intake hose and plug the air intake hose.
2. Connect a hand vacuum pump to the air purge hose.
3. With the engine idling, apply 14.8" vacuum.
Vacuum should NOT leak.
4. Increase the rpm to 3000, apply 14.8" vacuum.
Vacuum should NOT leak.

WARM ENGINE TEST - Coolant temperature above 70°C (158°F)
1. Disconnect the air purge hose from the air intake hose and plug the air intake hose.
2. Connect a hand vacuum pump to the air purge hose.
3. Increase rpm to 3000 within three minutes of engine start-up. Try applying vacuum.
Vacuum should leak.
4. Decrease engine rpm to idle, apply 14.8" vacuum.
Vacuum should NOT leak.
5. Increase rpm to 3000 after three minutes have elapsed from engine start-up. Apply 14.8" vacuum.
Vacuum will be maintained momentarily, after which it will leak.

NOTE: Vacuum will leak continuously if altitude is higher than 7,200 ft. (2,200 m) or if the intake air temperature is higher than 122°F (50°C).



PURGE PORT VACUUM CHECK
This test should be done first, when the Purge Control Solenoid is suspected to be faulty.

Purge Port Vacuum Test:

With the engine stopped.
1. Disconnect the vacuum hose from the throttle body purge hose nipple.
2. Connect a hand vacuum pump to the nipple.
3. Start the engine and note the vacuum reading.
4. Increase the engine speed sharply and note the vacuum reading.
Vacuum should remain fairly constant through out the test.
If there is no vacuum, the throttle body port may be clogged and will need to be cleaned.



PURGE CONTROL SOLENOID VALVE

1. Disconnect the vacuum hoses (non-stripe and red stripe) from the solenoid valve.
2. Disconnect the electrical harness connector from the solenoid valve.

Testing The Purge Control Solenoid Valve:

3. Connect a hand vacuum pump to the red striped hose nipple.
4. Connect jumper wire leads to the purge control solenoid terminals.
5. Apply a vacuum to the solenoid valve.
Vacuum should leak.

Purge Control Solenoid Valve Voltage Test:

6. Apply vacuum while applying voltage directly to solenoid.
Vacuum should NOT leak.

Purge Control Solenoid Valve Resistance Check:

7. Measure the resistance between the terminals of the solenoid valve.
Refer to ELECTRICAL SPECIFICATIONS.


PURGE CONTROL VALVE

Purge Control Valve Test:

1. Remove the Purge Control Valve.
2. Lightly blow air into canister side nipple. Air should not pass through.
3. Connect a vacuum pump to the vacuum nipple of the purge control valve.
4. Apply 8.0" vacuum and lightly blow air into the valve from the canister side. Air should pass through.

Purge Control Valve Test:

5. Connect the vacuum pump to the positive pressure nipple of the purge control valve.
6. Apply 15.7" vacuum to check for air tightness.



OVERFILL LIMITER/TWO-WAY VALVE

Check Valve Testing:

1. Remove overfill limiter/two-way valve from the vapor line.
2. Connect a hand vacuum pump to the inlet side.
3. Apply vacuum. Vacuum should NOT leak.
4. Repeat the test for the other side of the valve.
5. Vacuum should LEAK.