DESCRIPTION
System prevents escape of fuel vapor into atmosphere. Components include a check and cut valve (located at fuel tank), check valve (turbo only), charcoal canister, purge valve and connecting hoses.
OPERATION
With engine not running, fuel vapor from fuel tank and engine is stored in the charcoal canister. With engine operating above idle, purge valve opens. Fuel vapor is then drawn from charcoal canister and engine into the intake manifold.
Turbo Vehicles
Check valve prevents airflow from airflow meter back into charcoal canister.
CHECK & CUT VALVE
Check and cut valve controls fuel tank pressure to prevent fuel tank damage.
PURGE VALVE
Vacuum operated purge valve directs crankcase, fuel tank, and canister vapors into intake manifold when the throttle is opened.
Scheme 1
MAINTENANCE
Check entire system for operation and hose condition every 5 years or 60,000 miles. Replace all hoses and tubes every 5 years or 60,000 miles. Replace parts as necessary.
EVAPORATION LINE
Disconnect hose leading from charcoal canister to fuel tank. Connect a vacuum pump to the hose. Apply vacuum and note if vacuum is held. No vacuum should be held. If vacuum is held, test check and cut-valve and evaporation hose for blockage.
Note direction of valve installation. Remove check valve. Blow air into both ends of valve. Air should flow through valve from charcoal canister side, but should not flow from airflow meter side (beveled end). Replace valve if defective.
- Remove check and cut valve. Connect a pressure gauge with "T" fitting on nipple leading to fuel tank. Cap opposite nipple. (Scheme 2)
- Blow through passage "A". When pressure gauge reads.14-.71 psi (.01-.05 kg/cm 2 ), valve should open. Remove "T" fitting and pressure gauge. Connect "T" fitting to bottom of valve. Blow through passage "B". When pressure gauge reads.78-1.0 psi (.06-.07 kg/cm 2 ), valve should open. Replace assembly if valve did not open at specified pressure.
Scheme 2
Disconnect hose from purge valve to oil filler pipe. (Scheme 3) Start engine and operate at idle. Place finger over opening. No vacuum should exist. Increase engine speed to 2000 RPM and note that vacuum now exists. If no vacuum exists, replace purge valve.
