Charcoal Canister
- Connect tachometer to engine. Start and warm engine to normal operating temperature. Remove fuel filler cap. Remove canister purge air hose from frame rail and connect vacuum gauge. See Fig 1 . Raise engine speed to 3500 RPM and observe vacuum gauge. Vacuum should appear within 1 minute. If vacuum appears, remove test equipment, install fuel filler cap, and reconnect hose.
- If no vacuum is present, or does not appear within 1 minute, stop engine. Disconnect vacuum gauge and install fuel filler cap. Remove charcoal canister and check for damage. Replace canister if defective and retest.
- If canister is not defective, disconnect upper vacuum hose from purge control valve port on canister. Connect hand vacuum pump to purge port and apply vacuum. Vacuum should remain steady. If vacuum drops, replace canister and retest.
- If vacuum remains steady, reconnect hose to purge control valve port. Start engine and run at idle. Purge port vacuum should drop to zero. If not, replace canister and retest.