1. EVAP VALVE IN FUEL TANK
2. TWO-WAY EVAP VALVE
3. EVAP PURGE SOLENOID
4. BLACK AND YELLOW WIRE
5. FUSE (15 A) IGNITION COILS
6. DIFFERENT SENSORS
7. ECM/PCM
8. RED WIRE
9. BLACK WIRE
10. EVAP PURGE DIAPHRAGM VALVE
11. FRESH AIR
12. EVAP CHARCOAL FILTER
13. FUEL FILLER CAP
14. FUEL TANK
1. EVAP VALVE IN FUEL TANK
2. TWO-WAY EVAP VALVE
3. (without RSU)
4. EVAP CHARCOAL FILTER
5. FRESH AIR
6. EVAP PURGE DIAPHRAGM VALVE
7. EVAP CHARCOAL FILTER
8. (with PCV)
9. FRESH AIR
10. FUEL FILLER CAP
11. FUEL TANK
Description
The EVAP system is used to reduce the emission of fuel vapors into the atmosphere. The system consists of the following components:
A. Carbon evaporative filter (EVAP). An EVAP carbon filter is used to temporarily store fuel vapors until they can be blown from the filter into the engine and burned.
B. Vapor Purge Control System. EVAP charcoal filter purge is accomplished by drawing fresh air through the EVAP charcoal filter and into the throttle body port. Purge vacuum is controlled by the EVAP purge diaphragm valve and the EVAP purge solenoid valve (on models with TWC).
C. The system for regulating the flow of fuel vapor from the fuel tank. When the fuel vapor pressure in the fuel tank is higher than the two-way EVAP valve setting, the valve opens and controls the flow of fuel vapor to the EVAP filter.
Examination (models without TWC)
1. Remove the fuel filler cap.
2. Start the engine and let it run at idle speed.
3. Disconnect EVAP purge diaphragm valve vacuum hose (with charcoal filter EVAP) and connect a vacuum gauge to the hose.
If there is no vacuum, check the vacuum hose for blockage, cracks, or disconnection, and the vacuum port for blockage.
4. Disconnect the gauge and connect a vacuum hose.
5. Connect a vacuum gauge to the EVAP carbon filter purge air hose.
6. Bring the engine speed up to 3500 rpm. After 1 minute, the instrument should indicate a vacuum.
- If the vacuum is registered by the device after 1 minute, remove the device, the test is completed.
- If there is no vacuum, disconnect the vacuum gauge and replace the filler cap.
7. Remove the EVAP carbon filter and check for signs of damage or defects.
- If damaged, replace the EVAP carbon filter.
8. Stop the engine. Disconnect the top vacuum hose from the EVAP purge diaphragm valve.
Connect the vacuum pump to the lower vacuum hose as shown in the illustration and apply a vacuum.
The vacuum must remain constant.
If the vacuum drops, replace the EVAP carbon filter and recheck.
9. Restart the engine. Reconnect the top vacuum hose to the EVAP purge diaphragm valve.
Vacuum (from the side of the lower vacuum hose) should drop to zero.
If the vacuum does not drop to zero, replace the EVAP carbon filter and recheck.
EVAP 2-Way Valve Test
1. Remove the fuel filler cap.
2. Disconnect the vapor tube from the two-way valve on the fuel tank and connect it to the tee from the vacuum gauge and vacuum pump, as shown in the figure.
3. Slowly create a vacuum and continuously observe the instrument readings.
The vacuum should instantly stabilize at 0.7-2.0 kPa (5-15 mmHg).
If the vacuum stabilizes (valve opens) below 0.7 kPa (5 mmHg) or above 2.0 kPa (15 mmHg), install a new valve and recheck.
4. Move the vacuum pump hose from the vacuum connection to the pressure connection, and the vacuum gauge hose from the vacuum side to the pressure side, as shown in the figure.
5. Slowly pressurize the vapor tube while observing the meter reading.
The pressure should stabilize at 1.3-4.7 kPa (10-35 mmHg).
- If the pressure stabilizes instantly (valve opens) at the level of 1.3-4.7 kPa (10-35 mmHg), the valve is fine.
- If the pressure stabilizes below 1.3 kPa (10 mmHg) or above 4.7 kPa (35 mmHg), install a new valve and recheck.