Evaporative Emissions System: Testing and Inspection

Engine

EVAP System Troubleshooting

EVAP System Troubleshooting

Special Tools Required

*Vacuum/Pressure Gauge, 0-4 inHg 07JAZ-001000B
*Vacuum Pump/Gauge, 0-30 inHg Snap-on YA4000A or equivalent, commercially available

1. EVAP canister purge valve check (open stuck):

EVAP canister purge valve check (open stuck)
-1. Disconnect the vacuum hose (A) from the EVAP canister (B), and connect a vacuum pump/gauge, 0-30 inHg, to the hose.





-2. Start the engine, and let it idle.
NOTE: The engine coolant temperature must be at least 149 °F (65 °C).

Is there vacuum?
-YES- Inspect the vacuum hose routing. If OK, replace the EVAP canister purge valve Service and Repair.
-NO- Go to step 2.

2. EVAP canister purge valve check (closed stuck):

EVAP canister purge valve check (closed stuck)
-1. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then continue to hold the engine speed at 3,000 rpm.

Is there vacuum?
-YES- Go to step 3.
-NO- Inspect the vacuum hose routing. If OK, replace the EVAP canister purge valve Service and Repair.

3. EVAP canister check:

EVAP canister check
-1. Turn the ignition switch to LOCK (0).

-2. Reconnect the vacuum hose to the EVAP canister.

-3. Remove the fuel fill cap.

-4. Disconnect the purge air hose (A) from the EVAP canister (B), then connect a T-fitting (C) and a vacuum gauge to the hose as shown.





-5. Start the engine and raise speed to 3,000 rpm.

Does vacuum appear on gauge within 1 minute?
-YES- Do the EVAP two way valve test. If it is OK, evaporative emission system would be OK.
-NO- Replace the EVAP canister Service and Repair.