For 1990-2009 cars

### Evaporative Emission (EVAP) Canister Purge System Inspection

Caution: Do not breathe the air through the EVAP component tubes or hoses. The fuel vapors inside the EVAP components may cause personal injury.

Important: Perform a careful visual inspection of the evaporative emission (EVAP) control system components and the connecting hoses before diagnosis of an EVAP system malfunction.

Important: The EVAP canister purge system does not perform purging unless the engine is sufficiently warmed up and the heated oxygen sensor (HO2S) is fully activated.

Failure of the EVAP canister purge system to pass any of the above checks indicates a possible malfunction that will require further inspection.

1. Allow the engine to cool to room temperature.
2. Start the engine.
3. Disconnect the purge hose from the EVAP canister.
4. Place a finger against the end of the disconnected hose and check for vacuum. Vacuum should not be felt when the engine coolant temperature is less than the normal operating temperature.
5. Connect the purge hose to the EVAP canister and warm the engine up to a normal operating temperature.
6. Disconnect the purge hose from the EVAP canister.
7. Place a finger over the disconnected hose and check for vacuum. Vacuum should be felt with the engine running at a normal operating temperature and at 1,500 RPM.

### Evaporative Emission (EVAP) Canister Inspection

1. Disconnect the vacuum hoses from the EVAP canister.
2. Blow air into the tank port (1) of the EVAP canister. There should be no restriction of air flow through the purge pipe (2) and the air port (3).
3. Replace the EVAP canister if the EVAP canister fails the check above. Refer to Evaporative Emission Canister Replacement .
4. Connect the vacuum hoses to the EVAP canister.

### Evaporative Emission (EVAP) Canister Purge Valve Inspection

1. Disconnect the electrical connector from the EVAP canister purge valve .
2. Using a digital multimeter (DMM) measure the resistance of the EVAP canister purge valve between both terminals. The resistance should be 28-36 ohms at 20°C (68°F).
3. Replace the EVAP canister purge valve if the resistance is not 28-36 ohms at 20°C (68°F). If the resistance is within specification, proceed to Step 4.
4. Disconnect the purge valve vacuum hoses.
5. Blow air into the lower port of the purge valve. Air should NOT pass through the EVAP canister purge valve and exit from the upper port.
6. Connect 12 volts DC to the terminals of the EVAP canister purge valve.
7. Blow air into the lower port (1) of the purge valve. Air should pass through the EVAP canister purge valve and exit from the upper port (2).
8. Replace the EVAP canister purge valve if the valve failed this inspection. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
9. Connect the purge valve vacuum hoses and the electrical connector.

### Evaporative Emission (EVAP) Canister Vent Valve Inspection

1. Remove the EVAP canister vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement .
2. Using a DMM, measure the resistance of the EVAP canister vent valve between both terminals. The resistance should be 25-30 ohms at 20°C (68°F).
3. Replace the EVAP canister vent valve if the resistance is not 25-30 ohms at 20°C (68°F). If the resistance is within specification, proceed to Step 4.
4. Blow air into the vent valve port that was connected to the EVAP canister air filter. Air should pass through the EVAP canister vent valve.
5. Connect 12 volts DC to the terminals of the EVAP canister vent valve .
6. Blow air into the vent valve port that was connected to the EVAP canister air filter. Air should not pass through the vent valve and exit from the other end.
7. Replace the EVAP canister vent valve if the vent valve failed this inspection.
8. Install the EVAP canister vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement .

### Fuel Tank Pressure Control Valve Inspection

Important: The fuel tank pressure control valve that is original equipment manufacture (OEM) is black on the fuel tank side port, and orange on the canister side port.

1. Connect a hose to the fuel tank side of the pressure control valve on the fuel tank.
2. Blow hard into the hose. Some air should pass through the valve from the fuel tank side to the canister side when blown hard.
3. Remove the hose from the fuel tank side, and connect the hose to the canister side of the pressure control valve.
4. Blow easily into the hose. Even lightly blown air should pass smoothly through the valve from the canister side to the fuel tank side.
5. Replace the fuel tank pressure control valve if the valve fails any of the above inspections. Refer to Fuel Tank Pressure Control Valve Replacement .