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Fuel EVAP System Test (Prius)

NOTE: Manufacturer provides testing information for testing airtightness of fuel tank and components along with testing of charcoal canister and fuel EVAP system.
WARNING: Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS .
  1. Inspect all fuel EVAP system lines and connections for sharp bends or damage. It may be necessary to remove tailpipe and heat insulator for access to lines and connections. 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. Start engine and warm engine to normal operating temperature. Shut engine off. Connect vacuum gauge from EVAP System Test Kit (00002-6872A) to EVAP service port. EVAP service port is located in engine compartment, in purge vacuum hose for EVAP system, near air cleaner assembly. EVAP service port contains a Green label for identification.
  3. Operate EVAP Vacuum Switching Valve (VSV). If Toyota hand-held tester is available to operate EVAP VSV, go to next step. If Toyota hand-held tester is not available to operate EVAP VSV, go to step  5.
  4. Connect hand-held tester to data link connector No. 3 at driver's side of instrument panel. See Figure. Start engine. Turn hand-held tester on. Select ACTIVE TEST MODE on hand-held tester. Using hand-held tester manufacturer's instructions, activate EVAP VSV. Go to step  6.
  5. Disconnect electrical connector at EVAP VSV. EVAP VSV is located at passenger's side front corner of engine compartment, near air intake hose and contains Blue 2-pin electrical connector with Red/Blue and Black wires. See Figure. Using jumper wires, connect battery voltage and ground to electrical terminals on EVAP VSV to operate EVAP VSV. Start engine. Go to next step.
  6. Check vacuum reading on vacuum gauge with engine idling. Vacuum reading should be .368-19.713 in. Hg (5.00-268.00 in. H2O) for over 5 seconds. If vacuum reading is within specification, go to next step. If vacuum reading 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 .
  7. Shut engine off. If using hand-held tester to operate EVAP VSV, stop operation of EVAP VSV. Leave hand-held tester connected to DLC No. 3. 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.
  8. Disconnect vacuum gauge from EVAP service port. Connect pressure gauge to EVAP service port. Install hose crimper on air drain hose near charcoal canister. See Fig 1. Charcoal canister is located near fuel tank. See Figure.
    Fig 1: Installing Hose Crimper On Air Drain Hose (Prius)
    G00025355Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  9. Apply 13.5-15.5 in. H2O of pressure to EVAP service port. After 2 minutes of applying pressure, pressure should be 7.7-8.8 in. H2O. If pressure is within specification, remove hose crimper and go to next step. If pressure cannot be maintained, remove hose crimper. 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 .
  10. To check airtightness of fuel tank and fuel inlet pipe, operate Canister Closed Valve Vacuum Switching Valve (CCV VSV). If Toyota hand-held tester is available to operate CCV VSV, go to next step. If Toyota hand-held tester is not available to operate CCV VSV, go to step  12.
  11. With hand-held tester still connected to data link connector No. 3, turn ignition on and then turn hand-held tester on. DO NOT start engine. Select ACTIVE TEST MODE on hand-held tester. Using hand-held tester manufacturer's instructions, activate CCV VSV. Go to step  13.
  12. Remove glove box for access to Engine Control Module (ECM). For illustration of ECM location, see THEORY & OPERATION article. Turn ignition on. Connect jumper wire between body ground and terminal No. 13 (Blue wire) at ECM electrical connector E9. See Fig 2. This is the CCV terminal at ECM which is the ground circuit for the CCV VSV. Go to next step.
    Fig 2: Connecting Jumper Wire At Engine Control Module (Prius)
    G00028762Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  13. Apply .232 psi (.016 kg/cm2 ) of pressure to EVAP service port. Check that pressure can be held for 30 seconds. If pressure can be held for 30 seconds, turn ignition off. Remove pressure gauge and hand-held tester or jumper wire. Go to next step. If pressure cannot be held for 30 seconds, 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. Go to next step.
  14. To check air inlet line, disconnect air inlet line hose from fresh air valve and air cleaner case. See Fig 3. Fresh air valve is located on top of fuel tank. See Figure. Apply air pressure to air inlet line hose at air cleaner case. Ensure air flows from air inlet line hose at fresh air valve. If air flows from air inlet line hose, go to next step. If air does not flow from air inlet line hose, check for restrictions or damage to air inlet line and air inlet line hoses. If air inlet line or air inlet line hose is restricted, replace components as necessary.
  15. Inspect air inlet line hoses and air inlet line for damage. If air inlet line and air inlet line hose are okay, reinstall air inlet line hoses. Go to next step. If air inlet line or air inlet line hose is defective, replace components as necessary.
    Fig 3: Disconnecting Air Inlet Line Hoses (Prius)
    G00011336Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  16. To check charcoal canister, manufacturer states to remove fuel tank for access to charcoal canister. See FUEL PUMP under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article for removal of fuel tank. Disconnect necessary hoses for removal of charcoal canister if not previously done. Remove purge flow switching valve Vacuum Switching Valve (VSV) and retaining bolts for charcoal canister. Remove charcoal canister from fuel tank. Inspect charcoal canister for cracks or damage. If charcoal canister is okay, go to next step. If charcoal canister is defective, replace charcoal canister.
  17. Note ports on charcoal canister. See Fig 4. While holding port "C" closed, apply .71 psi (.05 kg/cm2 ) air pressure to port "A". Ensure air flows freely from port "B".
  18. Apply .71 psi (.05 kg/cm2 ) air pressure to port "A". Ensure air flows freely from all other ports on charcoal canister. Replace charcoal canister if defective. Reinstall charcoal canister on fuel tank.
  19. To check trap filter and fresh air valve, manufacturer states to remove fuel tank (if not already done) for access to trap filter and fresh air valve, as they are mounted on top of fuel tank. See Figure. Disconnect necessary hoses and electrical connectors for removal of Canister Closed Valve Vacuum Switching Valve (CCV VSV) and fresh air valve. Remove bolt and separate fresh air valve from CCV VSV. Remove bolts for CCV VSV and remove CCV VSV along with trap filter. Remove bolts and separate trap filter from CCV VSV.
  20. Inspect trap filter and fresh air valve for cracks or damage. If trap filter and fresh air valve are okay, go to next step. If trap filter or fresh air valve is defective, replace components as necessary.
  21. To check trap filter operation, apply light air pressure to port "A". Ensure air flows freely from port "B". See Fig 4. Replace trap filter if defective. To check fresh air valve operation, apply light air pressure to port "A". Ensure air flows freely from ports "B" and "C". See Fig 4. Replace fresh air valve if defective. Reinstall components on fuel tank.
  22. If fuel EVAP system operates properly, it may be necessary to check operation of EVAP Vacuum Switching Valve (VSV), canister closed valve Vacuum Switching Valve (VSV), purge flow switching valve Vacuum Switching Valve (VSV) and vapor pressure sensor. See EVAP VACUUM SWITCHING VALVE , CANISTER CLOSED VALVE VACUUM SWITCHING VALVE , PURGE FLOW SWITCHING VALVE VACUUM SWITCHING VALVE  and VAPOR PRESSURE SENSOR .
    Fig 4: Identifying Ports On Charcoal Canister, Trap Filter & Fresh Air Valve (Prius)
    G00011380Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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