Subaru 1600 Service Manual page 133

5) Automatic Choke
The choke valve is linked to the
bimetal through a choke lever so that
the choke valve is kept opened at the
degree corresponding to the ambient
temperature by means of the bimetal
force.
When the engine is started, the vacuum
diaphragm is operated by vacuum
pressure and the choke valve is opened
through a vacuum piston whereby the
. overchoke is prevented.
On all California models and non-4WD
of non-Califomia models, when the
engine is started with coolant tempera-
ture under ISoC (S9°F), solenoid valve
III opens the passage to air cleaner
until coolant temperature reaches
2SoC (77°F), and this reduces the
travel of vacuum position.
On all Canada models and 4WD of
non-California models, the travel of
the vacuum piston is reduced when the
coolant temperature drops below lSoC
(64°F).
After the engine is started, the bimetal
is warmed by the heater to adjust the
opening of the choke valve auto·
matically.
• Secondary Side
1) Step System
FUEL
I
Float chamber
J
I
. . .
FUEL SYSTEM
All California models
and non-4WD of
non-California models
r----..J
ld _ _ _
1 Diaphragm chamber
2
Chocke valve
3
Vacuum piston
4 Connecting rod
S Setting point is one notch to
rich side (10 degrees/notch)
6
Heater
Fig. 4-13
AIR
I
Air horn
I
I l
7
8
9
10
11
12
13
J
I
Main jet (secondary)
r
Economizer air Slow air bleed
~ bleed (secondary) (secondary)
I
,
b
Slow jet (secondary)
,
,
, J
I
Step system passage
I
~
j
I
Step hole
I
~
l
Throttle bore (secondary)
I
Fig.4-14 Fuel and ai, flow in the step system
AS·380
To air cleaner
t
Choke lever
A8-493
'Bimetal
Solenoid valve III
Intake manifold
Thermo vacuum valve II
ECM
Thermosensor
NOTE:
As for the construction, refer to 1 )
Slow system in Primary Side.