Evaporative Emissions System: Testing and Inspection

Fig. 4 Tank pressure control valve check:

TANK PRESSURE CONTROL VALVE

1. Remove rubber hoses from valve, Fig. 4.
2. Apply vacuum to pipe (A) and blow air into inlet pipe (B). Ensure valve is open.
3. Apply pressure to inlet pipe (B) with outlet pipe (C) capped. Ensure air does not pass through valve.
4. If valve does not operate as specified, replace valve as required.

Fig. 5 Applying pressure to purge control valve:

Fig. 6 Applying vacuum to purge control valve:

CHARCOAL CANISTER

1. Remove charcoal canister.
2. Inspect canister for cracks or damage. Replace canister, if necessary.
3. Check operation of purge control valve as follows:
a. Apply approximately 14 psi (50 kPa) to port marked V.C., Fig. 5. No air should leak from diaphragm.
b. Apply approximately 14.96 inches Hg vacuum to port marked PURGE and maintain vacuum, Fig. 6.
c. Apply vacuum gradually to the port marked V.C. If the purge control valve begins to open (vacuum gauge reading on the PURGE port decreases) at a pressure between 1.6 and 3.2 inches Hg vacuum, the purge control valve is functioning normally.
4. If valve operation is not as specified, replace charcoal canister.