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.