1987 MAZDA 626 temperature

FUEL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Air flow meter
Detects amount
of
intake
air;

sends signal
to
engine control unit Intake
air
thermo sensor and fuel pump
switch
are
integrated

Atmospheric pressure sensor
Detects atmospheric pressure; sends sig-nal
to
engine control unit

Circuit opening relay
Voltage
for
fuel pump while engine running

Clutch switch
Detects in-gear condition; sends signal
to
engine control unit Switch
ON
when clutch pedal released

Engine control unit
Detects signals from input sensors and switches; controls injector operation

Fuel filter
Filters particles from fuel

Fuel pump
Provides fuel
to
injectors • Operates while engine running
• Installed
in
fuel tank

Idle switch
Detects when throttle valve fully closed;
sends signal
to
engine control unit
Installed
in
throttle sensor

Ignition coil (-) terminal
Detects engine speed; sends signal
to
engine control unit

Ignition switch (ST position)
Sends engine cranking signal
to
engine control unit

Inhibitor switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON in "N" or "P"
range

Injector
Injects fuel into intake port • Controlled
by
signals from engine control unit • High-ohmic injector

Intake air thermo sensor
Detects intake
air
temperature;
sends signal
to
engine control unit Installed
in air
flow meter

Main relay
Supplies electric current
to
injectors and engine control unit

Neutral switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON
in-gear

Oxygen sensor
Detects Oxygen concentration; sends sig-nal
to
engine control unit
Zirconia ceramic and platinum coating

Pressure regulator
Adjusts fuel pressure supplied
to
injectors

Pulsation damper
Absorbs fuel pulsation

Throttle sensor
Detects throttle valve opening angle; sends signal
to
engine control unit
Integrated idle switch

Water thermo sensor
Detects coolant temperature;
sends signal
to
engine control unit

Water thermo switch
Detects radiator coolant temperature; sends signal
to
engine control unit ON: above 17°C (63°F)

76G04B-058
4B—43

4B FUEL SYSTEM
76G04B-061
I i. i { 1 t' i 1 I • i i 1 1 "1 —r
1 . . • , 1 ,
EDO 250
86U04A-074
w Test connector
(Yellow)
86U04A-075
Lever
To fuel pump To pulsation damper
FUEL PRESSURE
Note
a) When inspecting fuel pressure, use the
SST. (Refer to page 4B—47).
b)Warm up the engine to normal operating
temperature.
Injection Pressure
1. Set the lever on the adapter as shown in the figure.
2. Run the engine and measure the injection pres-
sure at various speeds.
Injection pressure: Approx. 235—275 kPa
(2.4—2.8 kg/cm2, 34—40 psi)
3. If not within specification, check the fuel pump pres-
sure and fuel line pressure.
Fuel Pump Pressure
1. Connect the terminals of the test connector (Yel-
low) with a jumper wire.
2. Turn the ignition switch ON to operate the fuel
pump.
3. Set the lever on the adapter as shown in the figure.
4. Check the fuel pump pressure.
Fuel pump pressure: 441—588 kPa
(4.5—6.0 kg/cm2, 64—85 psi)
5. If the fuel pump pressure is not within specifica-
tion, check the following;
No pressure
• Fuel pump operation (Refer to page
4B—49.)
Low pressure
• Fuel pump feeding capacity (Refer to
page 4B—50.)
High pressure
• Replace the fuel pump
6. After checking the fuel pump pressure, disconnect
the jumper wire from the test connector.
76G04B-062
4B—48

FUEL SYSTEM 4B
PRESSURE REGULATOR CONTROL SYSTEM
Water thermo sensor
*
Fuel
(To fuel tank)
76G04B-072
To prevent percolation of the fuel during idle after the engine is restarted, vacuum is cut to the pres-
sure regulator, increasing the fuel pressure.
Specified time: Approx. 120 sec.
Operating condition: Coolant temperature — above 70°C (158°F)
Intake air temperature — above 10°C (50°F)
4B—53

4B FUEL SYSTEM
COMPONENT DESCRIPTIONS
Component Function Remarks
Engine control unit Detects signals from input sensors and
switches; controls solenoid valve (Pres-
sure regulator control)
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed in throttle sensor
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Ignition switch
(ST position)
Sends engine cranking signal to engine control unit
Intake air thermo sensor Detects intake air temperature; sends signal to engine control unit
Installed in air flow meter
Pressure regulator Adjusts fuel pressure supplied to injectors
Solenoid valve (Pres-sure regulator control) Controls vacuum line to pressure regulator Closes vacuum line when hot
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
76G04B-073
4B—54

4B DECELERATION CONTROL SYSTEM
DECELERATION CONTROL SYSTEM
This system consists of the dashpot and fuel cut system. The dashpot is to prevent after-burn so that
the throttle valve gradually closes during deceleration.
The control unit detects engine deceleration judging from the engine speed and the idle switch, and
signals a fuel cut operation to match the engines need, based on the coolant temperature and the
driving condition.
4B—64

DECELERATION CONTROL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Brake light switch Detects braking operation (deceleration);
sends signal to engine control unit
Clutch switch Detects in-gear condition;
sends signal to engine control unit Switch ON when clutch pedal released
Dashpot (MTX) Prevents sudden closing of throttle valve during deceleration or shifting Adjustment speed: 1,900—2,100 rpm
Engine control unit Detects signals from input sensors and switches; cuts fuel injection
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed in throttle sensor
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Neutral switch Detects in-gear condition; sends signal to engine control unit Switch ON when in-gear
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch Detects radiator coolant temperature; sends signal to engine control unit ON: above 17°C (63°F)
76G04B-089
4B—65

EGR SYSTEM 4B
EXHAUST GAS RECIRCULATION
(EGR)
SYSTEM
EGR modulator valve Solenoid valve (EGR)
86U04A-127
This system introduces exhaust gas into the intake manifold to reduce NOx in the exhaust gas. It oper-
ates depending on the engine load, engine speed (above 1,500 rpm), engine coolant temperature
(above 70°C, 158°F), and radiator coolant temperature (above 17°C, 63°F).
COMPONENT DESCRIPTIONS
Component Function Remarks
EGR control valve Recirculates portion of exhaust gas
EGR modulator valve Controls vacuum acting on EGR control
valve
Engine control unit Detects signals from input sensors and switches; controls solenoid valve (EGR)
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Solenoid valve (EGR) Controls vacuum line to EGR control
valve
Throttle sensor Detects throttle valve opening angle; sends signal to engine control unit Integrated idle switch
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch Detects radiator coolant temperature; sends signal to engine control unit
ON: above 17°C (63°F)
76G04B-102
4B-71

4B EEC SYSTEM
EVAPORATIVE EMISSION CONTROL
(EEC)
SYSTEM
Engine control unit
Solenoid valve
(Purge control)
Vacuum
switch
valve x
From water thermo valve To dynamic -chamber
Three-way
check valve
Orifice Charcoal
canister
From fuel tank
No.2 purge
control valve
Fuel tank
86U04A-136
This system stores fuel vapor generated in the fuel tank in the canister when the engine is not running.
The fuel vapor is stored in the canister until it is drawn into the dynamic chamber and burned when
the engine is started.
COMPONENT DESCRIPTIONS
Component Function Remarks
Air flow meter Detects amount of intake air; sends signal to engine control unit
Intake air thermo sensor and fuel pump
switch are integrated
Charcoal canister Stores fuel tank fumes when engine
stopped
Engine control unit Detects signals from input sensors and switches; controls solenoid valve (Purge control)
Ignition coil (-)
terminal Detects engine speed; sends signal to
engine control unit
Separator Prevents fuel from flowing into charcoal canister
Solenoid valve (Purge control) Controls vacuum line to vacuum switch valve
Three-way check valve Controls pressure in fuel tank
Vacuum switch valve Regulates evaporative fumes from canis-
ter to intake manifold
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo valve Controls vacuum applied to No.1 purge control valve and solenoid valve (Purge control)
Opens vacuum line above 54°C (129°F)
76G04B-104
4B—74