Subaru 2009 IMPREZA Service Manual page 827

Diagnostic Trouble Code (DTC) Detecting Criteria
Valve Operation and Air Flow
In the figure below, divided by the diaphragm, the part above X is charged with atmospheric air pressure, and
the part below X is charged with tank pressure. Also, the part above Y is charged with tank pressure, and the
part below Y is charged with canister pressure.
If the atmospheric air pressure port is A, tank pressure port is B, and canister pressure port is C, the air flows
according to pressure difference from each port as shown in the table below.
(b)
(a) Barometric pressure
Condition of pressure
A < B (solenoid OFF)
B < C (solenoid OFF)
Solenoid ON
When A < B (solenoid OFF)
(b)
(a) Barometric pressure
B
X Y
(b) Fuel tank
Flow
B C
C B
B C
B
(b) Fuel tank
GD(H4SO)-103
A
(a)
C
X
(c) Canister
A
(a)
C
(c) Canister
GENERAL DESCRIPTION
(c)
EN-01716
(c)
EN-01717