Technical Description

To judge if there is a leak in the fuel system, the ECM (M/T) or PCM (A/T) measures the change of pressure in the fuel tank.
The ECM (M/T) or PCM (A/T) turns the evaporative emission ventilation solenoid on to shoot off the evaporative emission canister outlet port.
Then the evaporative emission purge solenoid is driven to set the fuel system into a negative pressure.
When the fuel system develops a vacuum of 0.29 psi (2 kPa), the evaporative emission purge solenoid is turned off and the fuel system vacuum is maintained at 0.29 psi (2 kPa).
The ECM (M/T) or PCM (A/T) determines if there is a leak in the fuel system by measuring the change of vacuum inside the fuel tank.
The test is stopped when fuel vapor pressure is judged as too high.