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 hose from the intake manifold vacuum source and apply an external vacuum of approximately 2-4 in. Hg. The trap door should open.
2. If the door does not open, apply vacuum directly to the vacuum motor on the air cleaner intake duct. If the door still does not open, inspect for binding/distortion and adjust as necessary. Replace the motor if the door swings freely.
3. If the door opens during the step above, inspect the vacuum hose for obstruction, cracks and kinks. Correct as necessary and retest.
4. If the vacuum hose is not defective, remove the reverse delay valve, join the vacuum hoses with an adapter and retest as described above. If the door opens, replace the reverse delay valve.