With Tank Pressure Control Solenoid Vacuum Valve

An evaporative emission control system is used to prevent emission of fuel vapor. The vapor generated in the fuel tank while driving or the engine at a stop passes through a tank pressure control valve and enters the EVAP canister where the charcoal absorbs and stores the fuel vapor. EVAP canister is purged or cleaned in the same way as EVAP control system for vehicle not equipped with tank pressure control solenoid vacuum valve. Tank pressure control valve operates as follows: As tank pressure control solenoid vacuum valve closes under the following either condition, vapor passage of tank pressure control valve also closes.
- Engine stops or
- Engine is running, vehicle stops and fuel level is higher than specified.

Therefore, when the pressure of the vapor generated in the fuel tank increases higher than specified pressure, it pushes open the tank pressure control valve and enters EVAP canister. However, under the conditions that the engine is running and the fuel level is lower than the specified level (or vehicle is running and fuel level is higher than the specified level), tank pressure control solenoid vacuum valve is turned ON by ECM and vacuum is applied to the diaphragm of tank pressure control valve. Thus, the vapor passage of tank pressure control valve opens to allow continuity between the fuel tank and EVAP canister. The EVAP canister air valve and the fuel tank pressure sensor are installed so that ECM diagnoses leakage of the fuel vapor from the evaporative emission control system. The EVAP canister air valve is usually open but it is closed by ECM when checking such leakage.