Evaporative Emissions System: Testing and Inspection
Testing Charcoal Canister:
CHARCOAL CANISTER
1. Remove charcoal canister.
2. Visually inspect canister for cracks or other damage.
3. Check purge control valve for proper operation.
a. Apply approx. 50Kpa pressure (7.25 psi) to the port marked "V.C."
b. Check that there is no air leakage from the diaphragm.
c. Apply approx. 380mmHg (15"Hg) vacuum to the port marked "purge" and maintain.
d. Gradually apply vacuum to the port marked "V.C." If the purge port begins to open when vacuum at the "V.C." port is between approx. 40-80 mmHg (1.6"-3.2"Hg), the purge control valve is operating normally.
f. If problem is found, replace canister.
Tank Pressure Control Valve:
FUEL TANK PRESSURE CONTROL VALVE
1. Remove rubber hoses.
2. Apply 56-63mmHg (2.3"-2.5"Hg) vacuum to control vacuum port. Vacuum should hold without bleeding down.
3. Blow air into fuel tank port.
4. Check to see that the valve is open and air flows easily through valve.
5. Apply pressure of approx. 28 mmHg (1.1" Hg or 0.54 psi) to control vacuum port.
6. Check to see that air flow through valve is restricted severely, but a small amount of air does flow through valve (through bypass orifice).
Vacuum Reservior Tank (ECS System):
VACUUM RESERVOIR TANK
1. Disconnect vacuum hoses from tank.
2. Connect vacuum gauge to port leading to vacuum switching valve (port B).
3. Connect vacuum pump to port leading to vacuum source (port A).
4. Apply vacuum to port A, then disconnect pump from vacuum reservoir tank.
5. Gauge should show tank holding vacuum.
6. Replace if defective.
Vacuum Switching Valve (ECS System):
VACUUM SWITCHING VALVE
1. Remove VSV.
2. Connect vacuum pump to port B.
3. Block port A with finger tip and apply vacuum to port B. No vacuum should be felt at port A, and port B should be vented to the atmosphere (does not hold vacuum).
4. Energize solenoid by applying 12 volts DC.
5. Block port A with finger tip and apply vacuum to port B. Valve should hold vacuum until port A is opened.
6. Replace if defective.
NOTE: When re-installing VSV, be sure port B is connected to device and port A is connected to vacuum source. If connected improperly, a vacuum leak will result.
Vent Switching Valve:
VENT SWITCHING VALVE - NON TURBO ONLY
1. Disconnect and plug vacuum hoses from carburetor to ventilation valve, at valve.
2. Disconnect vapor hose from canister at carburetor float bowl vent.
3. Start engine and idle.
4. Disconnect vent switching valve electrical connector.
5. Connect vacuum pump to float bowl vent and apply vacuum. As vacuum is increased, a noticeable stumble or change in engine rpm should occur.
6. Reconnect vent switching valve electrical connector and repeat step 4. There should be no noticeable change in the way the engine runs.
7. If engine stumbles or slows while performing step 5, the valve is leaking or is defective. Repair or replace as necessary.
Ventilation Valve:
VENTILATION VALVE - NON TURBO ONLY
1. Remove valve.
2. Check to that no air flows through valve, to carburetor port (engine stop condition).
3. Connect vacuum pump to control vacuum port of valve, and apply approx. 100 mmHg vacuum (approx. 4"Hg vacuum).
4. With vacuum applied, check that no air flows through valve to carburetor port (idle or off idle condition).
5. Gradually decrease vacuum, as vacuum approaches 0 (at approx. 40mmHg-50mmHg/1.6"-2.0" vacuum, W.O.T. condition) the valve should open and let air pass through to the carburetor port.
6. When vacuum falls below approx. 20mmHg/0.8"Hg vacuum, the valve should close again.
7. Replace if found to be defective.
THERMAL VACUUM VALVE - NON TURBO ONLY
1. With the engine cold, check to see that no air will flow through valve.
2. Start engine and warm it to operating temperature.
3. Check to see that air now flows through valve.
4. Replace if found to be defective.