Fuel EVAP System Test
- Inspect all EVAP system lines and connections for sharp bends or damage. See Figure or Figure . Fuel inlet pipe may also be referred to as fuel filler pipe. Inspect fuel inlet pipe for cracks, damage or fuel leakage. Inspect fuel tank cap for cracks or deformed gasket. Replace components if defective or damaged.
- Start engine and warm engine to normal operating temperature. Shut engine off. Connect vacuum gauge from EVAP system test kit to EVAP service port. EVAP service port is located in engine compartment (under air filter housing), in the purge vacuum hose for EVAP system. See Figure or Figure .
- EVAP Vacuum Switching Valve (VSV) must be operated. If scan tool is available, go to next step. If scan tool is not available, go to step 5.
- Connect scan tool to Data Link Connector (DLC) No. 3. See Figure or Figure . Start engine. Turn scan tool on. Select ACTIVE TEST MODE on scan tool. Using scan tool manufacturer's instructions, activate EVAP VSV. Go to step 6.
- Disconnect EVAP VSV connector. EVAP VSV is mounted on air intake chamber and contains a Blue 2-pin electrical connector. See Figure. Using jumper wires, connect battery voltage and ground to EVAP VSV terminals. Start engine. Go to next step.
- Check vacuum reading on vacuum gauge with engine idling. Vacuum should be .368-19.713 in. Hg (1.24-66.4 kPa) for more than 5 seconds. If vacuum is within specification, go to next step. If vacuum is not within specification, check for loose or restricted vacuum hose to EVAP service port, or for malfunctioning EVAP VSV. To check EVAP VSV operation, see EVAP VACUUM SWITCHING VALVE .
- Shut engine off. If using scan tool to operate EVAP VSV, stop operation of EVAP VSV. Remove scan tool. Go to next step. If connecting battery voltage to EVAP VSV to operate EVAP VSV, disconnect jumper wires and reconnect electrical connector on EVAP VSV. Go to next step.
- Disconnect vacuum gauge from EVAP service port. Connect pressure gauge to EVAP service port. Locate charcoal canister under rear of vehicle, near fuel tank. See Fig 1 or Fig 2 . Install hose crimper on charcoal canister air drain hose. Air hose may be marked with a Yellow line indicating area to be crimped at.
- Apply 13.5-15.5 in.H2O of pressure to EVAP service port. After 2 minutes of applying the pressure, the pressure should be 7.7-8.8 in.H20. If pressure is within specification, remove hose crimper and go to next step. If pressure cannot be maintained, remove hose crimper and check for disconnected vacuum hose between EVAP VSV, charcoal canister and fuel tank. If vacuum hose is properly installed on EVAP VSV, charcoal canister and fuel tank, check for stuck open EVAP VSV. To check EVAP VSV operation, see EVAP VACUUM SWITCHING VALVE .
- With pressure still applied at EVAP service port, remove fuel tank cap and note pressure reading. Pressure should decrease when fuel tank cap is removed. If pressure decreases when fuel tank cap is removed, remove pressure gauge and go to next step. If pressure does not decrease when fuel tank cap is removed, remove pressure gauge and check for restricted vacuum hose between EVAP service port, charcoal canister and fuel tank. Repair or replace vacuum hose as necessary.
- To check airtightness of fuel tank and fuel inlet pipe, disconnect EVAP line hose from charcoal canister. See Fig 1 or Fig 2 . Apply .58 psi (.040 kg/cm2 ) air pressure to EVAP line hose so pressure inside the fuel tank is .58 psi (.040 kg/cm2 ). Check that pressure inside fuel tank holds steady for one minute.
- If pressure inside fuel tank holds steady for one minute, reinstall EVAP line hose on charcoal canister. Go to next step. If pressure inside fuel tank will not hold steady for one minute, check for leaking hoses or pipes at fuel tank and fuel inlet pipe, or for leaks at fuel tank or installed components on fuel tank. If no leaks exist, replace fuel tank and fuel inlet pipe. Reinstall EVAP line hose on charcoal canister. Go to next step.NOTE: Overfill check valve may also be referred to as fill check valve. Cut-off valve may also be referred to as fuel cut-off valve.
- To check overfill check valve and cut-off valve, disconnect purge line hose, air drain hose and EVAP line hose from charcoal canister. Install cap on air drain hose port. See Fig 1 or Fig 2 .
- Apply .58 psi (.040 kg/cm2 ) air pressure to purge line hose fitting on charcoal canister. See Fig 1 or Fig 2 . Ensure air flows from EVAP line hose when air pressure is applied to purge line hose fitting on charcoal canister. If fuel tank is full of fuel, air may not flow from EVAP line hose, as overfill check valve may be closed. Ensure fuel tank is not full of fuel when checking for airflow at EVAP line hose.
- If air flows from EVAP line hose, go to next step. If air does not flow from EVAP line hose, check for restrictions in EVAP line hose and vent line hose. If any hose is restricted, replace hose and recheck operation. If hoses are not restricted, replace overfill check valve and cut-off valve located on top of fuel tank. See Fig 1 or Fig 2 .
- Reinstall purge line hose, air drain hose and EVAP line hose on charcoal canister. To check air inlet line, disconnect air inlet line hose from charcoal canister. See Fig 1 or Fig 2 . Apply air pressure to air inlet line hose. Air should flow through air inlet line hose. If air flows through air inlet line hose, go to next step. If air does not flow through air inlet line hose, check for restricted air inlet line hose or air inlet line.
- Disconnect necessary electrical connectors and components for removal of charcoal canister. Disconnect purge line hose, EVAP line hose and air inlet line hose from charcoal canister.
- Push connector on vent line hose toward charcoal canister and pinch both sides of retainer on connector, and then disconnect vent line hose with connector from charcoal canister. See Fig 3.
- Remove charcoal canister and vapor pressure sensor retaining bolts. Remove charcoal canister. Inspect charcoal canister for cracks or damage at all hose fittings. If charcoal canister is okay, go to next step. If charcoal canister is defective, replace charcoal canister.
- To check charcoal canister, install cap on vent port on charcoal canister. See Fig 4. Apply .26 psi (.018 kg/cm2 ) air pressure to EVAP port while holding purge port closed. Ensure air flows freely from air drain port.
- Apply .26 psi (.018 kg/cm2 ) air pressure to EVAP port while holding air drain hose and purge port closed. See Fig 4. Ensure no air flows from air inlet port.
- Using vacuum pump, apply 1.01 in. Hg of vacuum to purge port. See Fig 4. Ensure vacuum does not decrease when air inlet port is closed, and that vacuum decreases when air inlet port is opened.
- While holding air inlet port closed, use vacuum pump to apply 1.01 in. Hg of vacuum to EVAP port. See Fig 4. Ensure air flows into purge port. Remove cap from vent port. Replace charcoal canister if defective.
- Reinstall charcoal canister. If fuel EVAP system operates properly, it may be necessary to check operation of EVAP Vacuum Switching Valve (VSV), vapor pressure sensor, pressure switching valve and canister closed valve VSV. See EVAP VACUUM SWITCHING VALVE , VAPOR PRESSURE SENSOR CIRCUIT , PRESSURE SWITCHING VALVE VACUUM SWITCHING VALVE and CANISTER CLOSED VALVE VACUUM SWITCHING VALVE .