EVAP Dual Check Valve
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The EVAP dual check valve allows purge flow during boost conditions. Fuel vapors flow through the EVAP dual check valve to the intake air system upstream of the turbocharger before entering the intake manifold. When the engine is OFF, or at atmospheric pressure, the EVAP dual check valve is in an indeterminate state.
There are 2 types of EVAP dual check valves on turbocharged engines. One type has the check valves integrated in a single housing assembly. The second type has separate check valves connected to a hose assembly with the EVAP ejector integrated with one of the check valves.