1987 SUZUKI GRAND VITARA glove box

[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.
1. Switch vent solenoid
2. Float
3. To canister
4. Inner vent passage
Fig. 4- l-4 Switch vent solenoid
Primary System
[Primary slow system]
The fuel, after passing through the main jet, is
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.
4-6

COMPUTER CONTROLLED EMISSION CONTROL SYSTEM
[Feed back system]
A prime purpose of this system is to maintain a controlled air fuel ratio, allowing the catalyst to reduce
oxides of nitrogen, hydrocarbons, carbon monoxide and to improve fuel economy simultaneously.
The electronic control module (ECM) and the oxygen sensor are provided in this system.
The oxygen sensor mounted on the exhaust manifold monitors the exhaust gas air fuel ratio and signals to
the ECM.
The ECM processes the oxygen sensor signal and controls carburetor air fuel ratio by the operation of the
mixture control solenoid in the carburetor.
Thus the signal of the exhaust gas air fuel ratio sensed by the oxygen sensor is fed back to ECM and the
carburetor air fuel ratio is controlled.
[Electronic control module (ECM)]
The ECM controls the fuel cut system, idle-up system, bowl vent system, EGR system and secondary
throttle valve system, as well as the feed back system. The ECM is located under the glove box of the
instrument main panel. Refer to Fig. 5-l -9.
I1
* Engine coolant
temperature
* Engine speed
-Electronic
controlmodule
I I
* Throttle positiont(Micro Switches)
I I I\-
* Fuel cut solenoid valve
-44
* Engine room
- * Vent solenoid valvetempe.rature
* Idle-up actuator (TWSV)* Electric load
* Secondary throttle valve (VSV) , _ ~
r* Mixture control
solenoid valve
* Barometric
pressure
+ ECM supply
voltage
* Gear position
Fig. 5-l-8Computer con trolled emissioncon trot s ys tern
5- 10

Checking feed back system
1) Operate (turn ON) cancel switch or check
l Defective oxygen sensor
l Defective mixture control solenoid valve
switch located at the place shown in belowl Defective carburetor or maladjusted idle
figure.mixture
-
1. Cancel switch (U.S.A.)Check switch (Canada)
2. Instrument panel
w
$
1
3. Steering columnholder bracket
4. Steering wheel
Fig. 5-3- 15 Cancel switch or check switch
2) Turn ignition switch
engine.
At this time, “CHECK
ON without running
ENGINE” light should
light (should not flash).
If it does not light, check electric circuit of
the light, namely light for blow off and lead
wire for disconnection.
Fig. 5-3- 16 “CHECK ENGINE” light
3) After lighting of the light is confirmed, start
engine and warm it up to normal operating
temperature.
4) When engine is warmed up, run engine at
1,500- 2,000 rpm. In this state, make sure
that “CHECK ENGINE”lightflashes. Flashing
of light proves that system is in good condition.
If light does not flash, it can be caused by
one of the following. Check them and replace
or adjust as necessary.
l Defective thermal switch
l Disconnected or loosely connected electric
lead wires of emission control systems
l Defective ECM
l Defective micro switches (idle and wot)
5)After making sure that “CHECK ENGINE”
light flashes, turn cancel switch OFF. Light
should go off.
6) Stop engine.
Checking idle and wide open micro switches
Check idle and wide open micro switches
according to the following procedures.
1. Warm up engine to normal operating tempe-
rature and stop engine.
2. For this check, use check terminal coming
from the lower right of instrument panel as
shown.
Connect negative prod of ohmmeter to check
terminal and positive prod to body.
Iht green wire
eck terminal
3. Instrument panel
4. Glove box lid
3. Turn ignition switch to “ON” position.
4. Observe ohmmeter indicator reaction to make
sure for the following movement for each
throttle valve position.
5-23