Choke System; When Coolant Temperature Is Low; When The Coolant Temperature Rises; Operation Of Choke System - Suzuki Samurai 1986 Service Manual

Choke System

This choke system is provided with a thermo-
wax which operates according to the heat from
the engine coolant, causing the choke valve to
open and close as well as the fast idle system to
operate automatically.
6
Fig. 4- I- 11 Choke system

[Operation of choke system]

As the thermo-wax is contracted at the low
coolant temperature, the plunger of the thermo-
wax is retracted (at the up position) and the fast
idle cam rotates clockwise by the spring force.
As a result, the cam follower pushed down by
the cam causes the primary throttle valve to
open and brings about the fast idle state.
The thermo-wax expands as the coolant tempe-
rature rises and the plunger position lowers,
causing the fast idle cam to rotate counterclock-
wise. As a result, the throttle valve starts moving
to close. In this way, the throttle valve closes
gradually as the coolant temperature rises until
it reaches the idling position at the normal
temperature. Refer to Fig. 4-l -11.
4-10

1) When coolant temperature is low:

As the thermo-wax is contracted and the
plunger is retracted, the choke valve linked
with the fast idle cam is closed. When the
engine is started in this state, the intake
manifold vacuum pulls the diaphragm of the
choke piston to the left (below figure). The
choke piston rod also moves to the left and
acts on the choke valve to open. However,
the choke valve is restricted by the plunger of
the thermo-wax through the choke lever.
8
Therefore, the rod cannot move to the left
far enough to open the choke valve wide and
has .to stop at a position where the choke
valve opening is small as shown in the figure.
In this state, the diaphragm contracts the
bucking spring.
1. Choke piston
2. Vacuum
3.
4. Plunger
5.
Fast idle cam
1. Choke piston
6.
Cam follower
2. Intake manifold vacuum
7. Throttle valve
3. Diaphragm
8.
Choke valve
4. Choke piston rod
Fig. 4- I- 12 When coolant temp. is low

2) When the coolant temperature rises:

The plunger lowers due to the expansion of
the thermo-wax. Then the fast idle cam rotates
counterclockwise and consequently the choke
lever clockwise. This allow the rod to move
further to the left by the bucking spring force
(below figure). Thus a wide opening of the
choke valve is obtained.
Hereafter, the plunger of the thermo-wax
moves futher down in accordance with the
coolant temperature rise. The lower the
plunger moves, the wider the choke valve
opening becomes, and it becomes fully open
at the normal coolant temperature.
5.
Choke valve
6.
Choke lever
7. Bucking spring