Miata 1990-1997

Evaporative Emission Control System

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Evaporative Emissions Purge Solenoid Valve



Operation

Specific to:

Mazda Miata 1990-1997

The Evaporative Emissions (EVAP) Control System prevents the evaporation of unburned fuel vapors (Hydrocarbons) from being released into the atmosphere. The Evaporative Emissions (EVAP) Canister contains a charcoal element for the filtering of hydrocarbons, and the filtered Carbon Dioxide (CO2) is then vented to atmosphere when the vehicle is not in operation.

When the vehicle is in operation, the Evaporative Emissions (EVAP) Purge Control Valve draws the unburned fuel vapors back into the fuel tank so that the hydrocarbons can be condensed, and redistributed to the engine for correct burning.

Testing

Specific to:

Mazda Miata 1990-1997

  1. Warm up the engine to normal operating temperature.
  2.  
  3. Run the engine at idle.
  4.  
  5. Disconnect the vacuum hose from the solenoid valve and verify that no vacuum is felt at the solenoid valve.
  6.  
  7. If not as specified, check the solenoid valve.

    Click image to see an enlarged view

    Fig. Testing the solenoid valve

  8.  
  9. Disconnect the solenoid valve connector and connect 12V and a ground to the terminals of the solenoid valve.
  10.  
  11. Verify that air flows through the valve.
  12.  
  13. If not as specified, replace the solenoid valve.
  14.  

EVAP Canister



Location

Specific to:

Mazda Miata 1990-1997

The vapor, or carbon canister is part of the evaporative emission control system. It is located in the right rear of the engine compartment.

Servicing

Specific to:

Mazda Miata 1990-1997

Servicing the carbon canister is only necessary if it is clogged or contains liquid fuel, indicated by odor or by excessive weight. Remove the canister and blow into the air vent in the bottom of the canister. If air passes from the fuel vapor inlet and the canister does not contain liquid fuel, it is okay. If replacement is necessary, the canister must be replaced as a unit; it cannot be disassembled.

 
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