Subaru XT 1988 Service Manual page 138

2-1
EMISSION CONTROL SYSTEM AND VACUUM FITTING
TWO-WAY VALVE
The two-way valve is located in the fuel vapor line and func-
tions to control the pressure in the fuel tank.
When the fuel tank pressure is positive above a certain point,
the valve A is open to perm it the fuel vapor to the canister,
and when the fuel tank pressure is negative below a certain
point, the valve B is open to introduce fresh air into the fuel
tank.
To canister
A10-084
Fig. 11
'\
FUEL SEPARATOR
The fuel separator is to prevent liquid fuel from flowing into
the canister in case of abrupt cornering, etc.
To canister
Fuel separator
L2-329
Fig. 12
10
FUEL CAP
The rei ief valve is adopted to prevent the development of
vacuum in the fuel tank which may occur in case of trouble in
the fuel vapor line.
In normal condition, the filler pipe is sealed at
®
and at the
packing pressed against the filler pipe end. As vacuum develops
in the fuel tank, atmospheric pressure forces the spring down
to open the valve; consequently air is led into the fuel tank
controlling the inside pressure.
~Handle
L2-1027
Fig. 13
INSPECTION
FUEL PIPING
Check fuel piping and connections for leakage.
EVAPORATION LINE FROM FUEL TANK TO
CANISTER
1) Remove fuel filler cap.
2) Disconnect evaporation line at evaporation pipe CPo
3) Check for unobstructed evaporation line on fuel tank side
except for a little resistance due to 2-way valve by blowing air
into hose.
4) Check for unobstructed evaporation line on canister side
with no resistance by blowing air into hose.
TWO-WAY VALVE
1) Check for air passage with slight resistance due to the
valve by blowing air into the nipple on the side marked with
letters "To engine".
2) Repeat the same step on the other nipple.
3) Check for the valve case with no crack. If cracked, replace
it with new one.