Primary System; Switch Vent Solenoid; Primary Slow System; Mixture Control Solenoid Valve - Suzuki Samurai 1986 Service Manual

[Switch vent solenoid]

Provided on top of the float chamber is a switch
vent solenoid which is connected to the ignition
switch through ECM. As the ignition switch is
operated, the solenoid opens and closes its valve
so as not to release the fuel vapor in the float
chamber out into the atmosphere.
When the ignition switch is turned to "OFF"
position, the passage connecting the inner vent
passage and the float chamber will close, and the
passage connecting the float chamber and the
canister will open, then the fuel vapor will flow
into the canister.
When the ignition switch is turned to "ON"
position, and engine speed is above 400 r/min,
the passage connecting the float chamber and
the canister will close, and the passage connect-
ing the float chamber and the inner vent passage
will open, then the fuel vapor will flow into the
carburetor bore.
Fig. 4- l-4 Switch vent solenoid
4-6
1. Switch vent solenoid
2. Float
3. To canister
4. Inner vent passage

Primary System

[Primary slow system]

metered by the primary slow jet, then mixed
with the air from the primary slow air No. 2
bleeder. This air/fuel mixture is further blended
with the air from the primary slow air No. 1
bleeder and air supplied through the mixture
control solenoid. Then the air/fuel mixture
passes through the idle down channel and enters
the carburetor bore through the off idle discharge
port and the idle discharge hole.

[Mixture control solenoid valve]

The primary system has the Mixture Control
Solenoid (MCS) Valve. In the MCS, there is a
plunger which makes 16 up and down move-
ments per second by the electrical signals from
the Electronic Control Module (ECM). That is,
when an electrical signal is received by the
solenoid, the plunger will move down and when
no signal is received, the plunger will move up
by the spring force.
When the plunger moves down, the air jet locat-
ed on the upper side of the mixture control
solenoid valve will open as shown in below
figure, allowing the air to flow into the idle
down channel. In this condition, the mixture
will become lean.
On the other hand, when the plunger is pushed
up by the spring, the air jet will close, shutting
off the air flow into the idle down channel. In
this condition, the mixture will become rich.
The up and down movement of the plunger at
the rate of 16 times per second to the signals
from the ECM controls the air/fuel mixture to
the optimum ratio at all times and as a result
helps to improve the emission and engine per-
formances, and fuel economy.
The ECM receives the electrical information
from the oxygen sensor installed to the exhaust
manifold and the engine operating condition
signals from other devices and sends out and
stops the electrical signal to the mixture control
solenoid valve to actuate the plunger up and
down 16 times every second. The ECM is locat-
ed under the glove box of the instrument panel.