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Home >> Lexus >> 1999 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Emission Systems & Sub-Systems >> Fuel Evaporation System >> Fuel EVAP System Test (RX300 Early Release)

Fuel EVAP System Test (RX300 Early Release)

  1. Inspect all EVAP system lines and connections for sharp bends or damage. 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.
  2. To check airtightness of fuel tank and fuel inlet pipe, disconnect EVAP line hose from charcoal canister. See Figure. 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.
  3. 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 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.
  4. To check overfill check valve and cut-off valve, disconnect purge line hose and EVAP line hose from charcoal canister, and install cap on air drain hose. See Figure.
  5. Apply .58 psi (.040 kg/cm2 ) air pressure to purge line hose fitting on charcoal canister. See Figure. 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.
  6. 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 Figure.
  7. Reinstall purge line hose and EVAP line hose on charcoal canister, To check air inlet line, disconnect air inlet line hose from charcoal canister. See Figure. 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.
  8. 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 Figure.
  9. 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.
  10. To check charcoal canister, install cap on vent port on charcoal canister. See Figure. Apply .26 psi (.018 kg/cm2 ) air pressure to EVAP port while holding purge port closed. Ensure air flows freely from air drain port.
  11. Apply .26 psi (.018 kg/cm2 ) air pressure to EVAP port while holding air drain port and purge port closed. See Figure. Ensure no air flows from air inlet port.
  12. Using vacuum pump, apply 1.01 in. Hg of vacuum to purge port. See Figure. Ensure vacuum does not decrease when air inlet port is closed, and that vacuum decreases when air inlet port is opened.
  13. While holding air inlet port closed, use vacuum pump to apply 1.01 in. Hg of vacuum to EVAP port. See Figure. Ensure air flows into purge port. Remove cap from vent port. Replace charcoal canister if defective.
  14. 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 and vapor pressure sensor Vacuum Switching Valve (VSV). See EVAP VACUUM SWITCHING VALVE (ALL MODELS) , VAPOR PRESSURE SENSOR CIRCUIT (ALL MODELS)  and VAPOR PRESSURE SENSOR VACUUM SWITCHING VALVE (ALL MODELS) .
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