Charcoal Canister
- Connect tachometer to engine. Start and warm engine to normal operating temperature. Remove fuel filler cap. Remove canister purge air hose from canister and connect vacuum gauge to port. See Fig 1 . Run engine at 3500 RPM.
- If vacuum appears on gauge within 1 minute, remove gauge and proceed to step 7). If not, stop engine, disconnect vacuum gauge, and reinstall fuel filler cap. Check charcoal canister for damage or defects. If defective, replace canister and retest.
- If canister is okay but there is no vacuum at 3500 RPM after 1 minute, disconnect hoses from "PCV" (purge control valve) port and "PURGE" port on canister. Connect vacuum pump/gauge to canister "PURGE" port and draw vacuum. Vacuum should remain steady. If vacuum drops, replace canister and retest.
- If vacuum holds steady, reconnect "PCV" hose to canister and start engine. Check that "PURGE" port vacuum drops to zero.
- If "PURGE" port vacuum does not drop to zero, remove hose from "PCV" port on canister and check for vacuum at hose. If vacuum is present at hose, replace canister and retest. If vacuum is not present at hose, recheck thermo valve operation or check purge cut-off solenoid valve operation.
- If "PURGE" port vacuum drops to zero, connect purge hose to vacuum gauge and run engine at 3500 RPM. If vacuum is present at hose, replace canister and retest. If vacuum is not present at hose, check hose for leaks and obstructions, and carburetor/throttle body port for blockage. Repair and retest.
- Connect vacuum pump to "TANK" port on canister and try to draw vacuum. Vacuum should not be present. If vacuum is present, replace canister and retest.