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 replacing 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
The charcoal canister is a sealed service-free unit.

Dual Function CTO:

CTO FUNCTIONAL TEST
Engine coolant temperature should be below 100° F.
^ Check vacuum lines for leaks and correct routing.
^ Disconnect vacuum line at TVS and connect it to a vacuum gauge.
^ Operate engine at approximately 1500 RPM. No vacuum should be indicated on gauge. If vacuum is indicated, replace DUAL CTO valve.
^ Operate the engine until the coolant temperature exceeds 115° F.
^ Accelerate the engine to 1500 rpm. The carburetor ported vacuum should be indicated on the vacuum gauge. If not, replace the DUAL CTO valve.

Air Cleaner Trap Door:

AIR CLEANER TRAP DOOR ASSEMBLY
1. Remove the vacuum supply hose from the trap door vacuum motor.
2. Connect auxiliary vacuum supply to vacuum motor.
3. Apply 15 inches of vacuum.
4. Release vacuum.
5. Trap door should open when vacuum is applied and close when vacuum is released. If door does not open, replace vacuum motor.






REVERSE DELAY VALVE
1. Remove the vacuum hose from the end of the valve that is not black in color and apply an external vacuum of approximately 2-4 in. Hg.
2. Using a stopwatch, note the time required for atmospheric pressure to pass through the valve and eliminate the vacuum.
3. Replace the valve if the time required to eliminate the vacuum is less than 4.5 seconds or more than 13.2 seconds.