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.

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.

Check/Relief Valve:

CHECK/RELIEF VALVE

1. Remove valve.
2. Connect vacuum pump to side of valve leading to fuel tank.
3. Apply vacuum. Valve should hold a maximum of 20mmHg vacuum ( 0.8"Hg vacuum).
4. Disconnect vacuum pump, and connect it to the other port on valve.
5. Apply vacuum. Valve should hold a maximum of 40mmHg vacuum ( 1.6"Hg vacuum).
6. Replace if defective.

Vent Switching Valve:

VENT SWITCHING VALVE


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.

Checking Ventilation Valve:

VENTILATION VALVE

1. Remove valve.
2. Check to see that air flows freely through B to C (see diagram).
3. Apply vacuum (approx. 40mmHg-45mmHg/1.6"-1.8" vacuum)
4. Check to see that air does NOT flow freely through B to C.
5. Valve should remain closed at higher vacuum.
6. Replace if found to be defective.