Evaporative Emission (EVAP) Vapor Blocking Valve
The EVAP vapor blocking valve is a normally open valve, electrically closed by the PCM, to isolate the fuel tank from the rest of the EVAP system. The EVAP vapor blocking valve will automatically open to relieve excess pressure or vacuum, in the fuel tank, if the pressure or vacuum reaches a maximum calibrated value.
Typical EVAP Vapor Blocking Valve