Evaporative Emissions System: Testing and Inspection

SYSTEM SERVICE
Ensure all vacuum hoses and electrical wires are routed clear of the exhaust manifold to prevent deterioration due to the high temperature. Vacuum hoses should always be a minimum of three inches from the exhaust manifold. When servicing the charcoal canister, mark then disconnect vacuum hoses from charcoal canister to ensure proper installation.

NOTE: Use only fuel resistant hoses when servicing the evaporative control system.



CHARCOAL CANISTER TEST
The charcoal canister is a sealed service-free unit. The canister control valve can be checked by disconnecting the 3/16 vacuum hose on the canister and connecting a vacuum source in its place. If the control valve cannot hold 10 inches of vacuum, the canister must be replaced.



COOLANT VACUUM SWITCH COLD CLOSED (CVSCC) TEST
1. Insure coolant temperature is below 75°F (24°C) and switch is installed in its proper location.
2. Disconnect the molded connector from the valve and attach a 1/8 inch hose. If it is possible to blow through the hose the valve is faulty and must be replaced.
3. With engine at normal operating temperature, if it is not possible to blow through the hose the valve is faulty and must be replaced.

Vapor Containing Air Cleaner Assembly (Some 4Bbl):

VAPOR CONTAINING AIR CLEANER ASSEMBLY

1. Remove the vacuum supply hose from the vapor containment door vacuum delay valve.
2. Connect auxiliary vacuum supply to delay valve.
3. Apply 15 inches of vacuum.
4. Release vacuum.
5. Vapor containment door should open when vacuum is applied and close within 40 seconds when vacuum is released. If door does not close or open, replace vacuum delay valve.