Quest 1995-1996

Evaporative Emission Control System

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Description & Operation



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

The Evaporative Emissions System is designed to eliminate the discharge of fuel vapor into the atmosphere. Fuel vapor from the fuel tank is drawn into the evaporative (EVAP) canister where it is temporarily stored, until it is purged from the canister to the engine, where it is burned during combustion.

The EVAP canister is located on the firewall at the driver-s side of the engine compartment on 1993-98 vehicles (except 1998 California emissions). On 1998 California emissions vehicles and 1999-00 vehicles, the EVAP canister is located under the vehicle.

Operation



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

Fuel vapor from the fuel tank flows through an in-line check valve and vapor line to the evaporative emissions (EVAP) canister, where it is temporarily stored while the engine is off. The check valve allows air to pass in and out of the fuel tank to equalize pressure, and prevents liquid fuel from being drawn into the EVAP canister in the event of a rollover accident. On 1999-00 vehicles, the check valve has been replaced by a vacuum cut valve, which prevents intake manifold vacuum from being applied to the fuel tank.

Under certain conditions when the engine is running, the stored vapor from the canister is drawn by intake manifold vacuum, through a purge valve and the vapor lines, into the intake manifold. The purge valve is controlled by either intake manifold vacuum, a solenoid which is controlled by the PCM, or a combination of the two, depending on the model year of the vehicle.

On 1999-00 models, an EVAP canister pressure sensor, EVAP canister vent control valve, a vacuum cut bypass solenoid, and a fuel temperature sensor have been added, due to the EVAP system monitor incorporated in the on board diagnostics (OBD-II) system of the PCM. These components allow the PCM to test EVAP system performance. The PCM will then store diagnostic trouble codes if a fault in the EVAP system is detected.

Click image to see an enlarged view

Fig. Evaporative emission system schematic-1993-95 vehicles



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Fig. Evaporative emission system schematic-1996-98 vehicles (except for 1998 California emissions)



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Fig. Evaporative emission system schematic-1998 California emissions



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Fig. Evaporative emission system schematic-1999-00 vehicles

Removal & Installation



EVAP Canister
Except 1998 California Emissions
  1. Disconnect both battery cables. Remove the negative cable first.
  2.  
  3. Remove the air cleaner-to-intake manifold hose.
  4.  
  5. Remove the air cleaner assembly.
  6.  
  7. Label and disconnect the vapor hoses from the canister.
  8.  
  9. Remove the bolt from the canister clamp.
  10.  
  11. Slide the canister out of the clamp and remove it from the vehicle.
  12.  
  13. The installation is the reverse of removal.

    Click image to see an enlarged view

    Fig. Removing the EVAP canister clamp bolt-1993-98 vehicles, except 1998 California emissions

  14.  

EVAP Canister Purge Control Solenoid

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

On 1996-98 vehicles (except for California emissions), the EGR control solenoid also controls canister purge vacuum. Please refer to Exhaust Gas Recirculation System, Removal and Installation, EGR Control Solenoid for the procedure.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the solenoid electrical connector.
  4.  
  5. Label and remove the vacuum hoses from the solenoid.
  6.  
  7. Remove the nut that attaches the solenoid to the bracket and remove the solenoid.
  8.  
  9. The installation is the reverse of removal.
  10.  

EVAP Canister Purge Valve
Except 1998 California Emissions

The EVAP canister purge control valve is part of the EVAP canister assembly, and must be replaced as a unit. Please refer to Removal and Installation, EVAP Canister for the procedure.

Fuel Check Valve

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

To replace the fuel check valve on 1993-98 vehicles (except 1998 California emissions):

  1. Remove the fuel tank. Please refer to Fuel System, Fuel Tank, Removal and Installation for the procedure.
  2.  
  3. Remove the hose connecting the valve to the canister vapor line.
  4.  
  5. Remove the hose connecting the valve to the fuel tank and remove the valve from the tank.
  6.  
  7. The installation is the reverse of removal.
  8.  

Vacuum Cut Valve

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

To replace the vacuum cut valve on 1998 California emissions and 1999-00 vehicles:

  1. Raise and safely support the vehicle securely on jackstands.
  2.  
  3. Remove the screws, bolts, and clips from the EVAP canister splash shield. Remove the shield.
  4.  
  5. Disconnect the vacuum cut bypass valve electrical connector.
  6.  
  7. Using a pair of pliers, release and reposition the two hose clamps at the vacuum cut valve.
  8.  
  9. Label and remove the two hoses from the vacuum cut valve.
  10.  
  11. Remove the vacuum cut valve and the vacuum cut bypass valve together.
  12.  
  13. Disconnect the two vacuum cut bypass valve hoses from the vacuum cut valve.
  14.  
  15. The installation is the reverse of removal.

    Click image to see an enlarged view

    Fig. Vacuum cut valve location-1999-00 vehicles

  16.  

Servicing



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

While the EVAP canister requires no maintenance, the factory recommends that the canister and related lines should be inspected every 30,000 miles (24,000 km) or every 24 months, whichever comes first. Any components that are cracked, brittle, or damaged should be replaced. Please refer to Driveability and Emission Controls, Emission Controls, Evaporative Emission Controls, Removal and Installation for the procedure.

Testing



Canister Purge Control Solenoid

Specific to:

Mercury Villager 1996-1998

Nissan Quest 1996-1998

On 1996-98 vehicles, EVAP canister purge vacuum is controlled by the EGR control solenoid. Please refer to Exhaust Gas Recirculation System, Component Testing, EGR Control Solenoid for the procedure.

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000


NOTE
Two jumper wires are required for the following tests. An in-line fuse holder with a 30 amp fuse should be spliced in the jumper wire that will be connected to the positive battery terminal to prevent possible damage to the battery, wiring, and components of the circuit being tested.

Canister Purge Control Valve
Except 1998 California Emissions

The EVAP canister purge control valve is part of the EVAP canister assembly. Please refer to Component Testing, EVAP Canister for the canister purge control valve test procedure.

Evaporative Emissions Canister
Except 1998 California Emissions

The EVAP canister and canister purge control valve are tested and replaced as an assembly.

  1. Remove the EVAP canister from the vehicle.
  2.  
  3. Visually inspect the canister. Replace it with a new one if there is any evidence of cracks or other damage.
  4.  
  5. Blow air into port A . There should be no airflow from ports B or C .
  6.  
  7. Connect a hand vacuum pump to port A and apply approximately 20 in. Hg (67 kPa) of vacuum to the port. If the port will not hold vacuum, replace the canister.
  8.  
  9. With vacuum still applied to port A , plug port D . Blow air into port C . There should be free airflow out of port B .
  10.  
  11. Remove the vacuum pump from port A and unplug port D .
  12.  
  13. Blow air into port D . There should be free airflow from port C .
  14.  
  15. If the canister fails any of the preceding tests, replace the canister.

    Click image to see an enlarged view

    Fig. View of EVAP canister with air cleaner-to-intake manifold hose removed-1993-98 vehicles (except for 1998 California emissions)



    Click image to see an enlarged view

    Fig. EVAP canister port designations-1993-98 vehicles (except for 1998 California emissions)

  16.  

Evaporative Hoses & Tubes

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

Inspect all system hoses and tubes for signs of damage or cracks. Any damage or leakage must be repaired.

Fuel Check Valve (Roll-Over Valve)

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

To test the fuel check valve on 1993-98 vehicles (except 1998 California emissions):

  1. Remove the fuel check valve from the vehicle.
  2.  
  3. Hold the valve in the upright (installed) position.
  4.  
  5. Blow air into the fuel tank port. There should be considerable resistance to airflow, but it should not be completely blocked.
  6.  
  7. Blow air into the canister port. There should be free airflow through the fuel tank port.
  8.  
  9. Tilt the valve 90°. Perform the previous airflow tests. There should be no airflow through either port.
  10.  
  11. Tilt the valve 180°. Perform the previous airflow tests. There should be no airflow through either port.
  12.  
  13. If the valve fails any of the preceding tests, replace the valve.
  14.  

Vacuum Cut Valve

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

To test the vacuum cut valve on 1998 California emissions and 1999-00 vehicles:

  1. Remove the vacuum cut valve from the vehicle.
  2.  
  3. Plug ports C and D .
  4.  
  5. Apply vacuum to port A and make sure there is no vacuum at port B .
  6.  
  7. Apply vacuum to port B and make sure there is no vacuum at port A .
  8.  
  9. Blow air into port B and check for resistance to flow out of port A .
  10.  
  11. Open ports C and D .
  12.  
  13. Blow air into port A and check for free airflow out of port C .
  14.  
  15. Blow air into port B and check for free airflow out of port D .
  16.  
  17. If the valve fails any of the preceding tests, replace the valve.

    Click image to see an enlarged view

    Fig. Port designation for vacuum cut valve testing-1998 California emissions and 1999-00 vehicles

  18.  

 
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