1987 MAZDA 626 check engine

THERMOSTAT 3B
THERMOSTAT
REMOVAL
1. Drain the engine coolant.
2. Disconnect the upper radiator hose, and water
thermo switch connector.
3. Remove the thermostat cover.
4. Remove the thermostat.
76G03B-010
76G03B-011
Sub valve Main valve
I
INSPECTION
Check the thermostat. Replace if necessary.
1. Visually check that the valve is airtight.
2. Place the thermostat and a thermometer in water.
3. Gradually heat the water and check the following:
Valve opening temperature
Sub valve : 78.5—81.5°C (173—179°F)
Main valve : 86.5—89.5°C (188—193°F)
Full open lift
Sub valve : 1.5 mm (0.06 in) min. at
100°C (212°F)
Main valve : 8 mm (0.31 in) min. at
100°C (212°F)
Valve closing temperature
Sub valve : 75°C (167°F)
Main valve : 83°C
(181
°F)
69G03B-012
76G03B-012
INSTALLATION
1. Install the thermostat into the thermostat case with
jiggle pin at the top.
2. Install a new gasket with the seal print side facing
the thermostat case.
3. Install the thermostat cover.
Tightening torque:
7—10 N-m (70—100 cm-kg, 61—87 in-lb)
4. Install the upper radiator hose and water thermo
switch connector.
5. Replenish the coolant.
6. Start the engine and check for leaks.
3B-9

4A
FUEL AND EMISSION
CONTROL SYSTEMS
(CARBURETOR)
OUTLINE 4A— 2
SYSTEM DIAGRAM 4A— 2
VACUUM HOSE ROUTING
DIAGRAM 4A— 5
EMISSION COMPONENTS
LOCATION 4A— 8
COMPONENT DESCRIPTIONS 4A—12
SPECIFICATIONS 4A—15
TROUBLESHOOTING GUIDE 4A—17
PARTS INSPECTION 4A—23
AIR CLEANER ELEMENT 4A—23
ACCELERATOR LINKAGE 4A—23
INTAKE MANIFOLD 4A—23
CHOKE CABLE 4A—23
FUEL SYSTEM 4A—24
TROUBLESHOOTING 4A—25
CARBURETOR 4A—26
FUEL PUMP 4A—35
FUEL TANK 4A—36
SEPARATOR 4A—37
TWO-WAY CHECK VALVE 4A—37
THREE-WAY CHECK VALVE 4A—37
FUEL FILTER 4A—37
IDLE SPEED AND IDLE MIXTURE.. 4A—38
ADJUSTMENT 4A—38
AUTO-RETURN CHOKE SYSTEM... 4A—40
TROUBLESHOOTING 4A—40
PTC HEATER SYSTEM 4A—42
TROUBLESHOOTING 4A—42
DECELERATION CONTROL SYSTEM 4A—45
TROUBLESHOOTING 4A—45
BYPASS AIR CONTROL SYSTEM.. 4A—48
DASH POT 4A—50
ANTI-AFTERBURN VALVE 4A—50
MAIN AIR BLEED CONTROL
SYSTEM 4A—51
SLOW FUEL CUT SYSTEM 4A—53
COAST ENRICHMENT SYSTEM .... 4A—54
COASTING LEANER SYSTEM 4A—56
AIR INJECTION SYSTEM 4A—58
INTAKE AIR TEMPERATURE CONTROL
SYSTEM 4A—60
TROUBLESHOOTING 4A—60
PURGE CONTROL SYSTEM 4A—63
VACUUM SWITCH VALVE 4A—63
EXHAUST GAS RECIRCULATION
(EGR) SYSTEM 4A—64
TROUBLESHOOTING 4A—65
POSITIVE CRANKCASE VENTILATION
SYSTEM 4A—67
PCV VALVE 4A—67
IDLE-UP CONTROL SYSTEM 4A—68
TROUBLESHOOTING 4A—70
IDLE-UP SOLENOID VALVE 4A—76
EVAPORATIVE EMISSION CONTROL
SYSTEM 4A—78
TROUBLESHOOTING 4A—79
IGNITION TIMING CONTROL
SYSTEM 4A-80
TROUBLESHOOTING 4A—81
CONTROL SYSTEM 4A-83
RELATIONSHIP CHART 4A—84
ENGINE CONTROL UNIT 4A—86
INHIBITOR SWITCH 4A—93
IDLE SWITCH 4A—93
VACUUM SWITCH 4A—94
WATER THERMO SWITCH 4A—95
EXHAUST SYSTEM 4A—96
76G04A-001

OUTLINE
4A

Previous

626
Unlead-
ed

fuel
O O O O O O X O O O X

Previous

626

Leaded
fuel
O X X O O X X X O X

New
626
FE
8
Valve
Unlead-
ed

fuel
o O O O O O X X O O O

New
626
Sin-
gapore

o O X O O m O
O

(FE

&
F8)
O
O

(FE

&
F8)
O O

New
626

Middle
East
o X X O O X X X X X O

New
626

General

X
O

(FE

& F8)
X O O X
O

(FE

&
F8)
O

(FE

&
F8)
O

(FE

&
F8)
X o

New
626
ECE
&

Hong
Kong
o O X O O * O O O O O o

Remark
• Adjustment
speed:

2,200

±
100
rpm
(in
neutral).
• MTX • Operation:
Coolant
tempera-

ture

more
than

50°C

(122°F).

Mechanical
type
Installed
on
carburetor.
Improvement
of
product
quality.

Function

Allows

throttle
to
gradually
close

during

deceleration.

Reduces

CO

and
HC
emission.

Detects

electrical
signal
from
in-
put
devices
and
controls
output
devices. Supplies
exhaust
gas
to
intake
manifold
to
reduce
NOx

Filters

fuel

Provides

fuel
to
carburetor.
Detects
when
throttle
valve
fully
closed. Opens
fuel

passage

to
secon-
dary
stage
of
carburetor.
Controls
shutter
valve
by
intake

air
temperature. Prevents
carburetor

icing.

Supplies
fresh
air
to
exhaust
manifold
to
reduce
CO
and
HC
emissions. Prevents
fuel
from
flowing
into

two-way

or
three-way
check

valve

Component

Dashpot Engine
Contorol
Unit

EGR

Control
Valve

Fuel

Filter

Fuel

Pump
Idle
Switch

Idle-up

Solenoid

Valve
Intake
Air
Temperature
Control
Valve

PTC

Heater

Reed

Valve

Separator

•a a> a -a .2-S
3
9-a a) 5 u- O UJ
z

Ox

111 IL •a c x" Ul
V (-
U.ps •o u.
-
X
_ X
I-
o-t-
s ®
s
*
o *
oo
x to
U. UJ
u.
T- oi CO
4 A—13

TROUBLESHOOTING GUIDE
4A

TROUBLESHOOTING GUIDE
F6 (GENERAL)
The Troubleshooting Guide lists the systems most likely to cause
a
given symptom. After finding the
system(s)
to
check, refer
to
the pages shown
for
detailed guides
for
each system.
\\ POSSIBLE CAUSE
\ PAGE


SYMPTOM
Air

cleaner
(Air
cleaner
element)
intake
air
temperature
control

system
Idle

adjustment
Fuel
system
(Carburetor,
Fuel
pump)

idle-up

control
system
Exhaust
system
Positive
crankcase
ventilation

system
Auto-return
choke
system

\\ POSSIBLE CAUSE
\ PAGE


SYMPTOM 4A—23 4A—60 4A—38 4A—24 4A—68 4A—96 4A—67 4A—40
1 Hard start
or
won't start (Cranks
OK)
1 2

2 Engine stalls During warm
up
3 2 1 4
2 Engine stalls After warm
up
4 2 5 1 3

3 Rough Idle During warm
up
3 2 1 4
3 Rough Idle After warm
up
3 2 5 1 4

4 High idle speed after warm
up
1 3 2

5 Poor acceleration, hesitation, or lack
of
power
1 2 3

6 Runs rough
on
deceleration
1

7 Afterburn
in
exhaust system
1

8 Poor fuel consumption
2 1 4 3

9 Fails emission test
2 1 4 5 3

76G04A-015
The numbers of the list show the priorities
of
inspections from the most possible to that with the lowest
possibility.
These were determined
on
the following basis:
• Ease
of
inspection
•
Most possible system
•
Most Possible point
in
system
TROUBLESHOOTING PROCEDURE:
1st Check the following items:
Electrical system
1) Battery condition
2) Fuses
Ignition system
1) Spark plugs
2) Ignition timing
Fuel system
1) Fuel level
2) Fuel leakage
3) Fuel filter
4) Idle speed
Intake
air
system
1) Vacuum
or air
leakage
2) Vacuum hose routing
3) Accelerator cable
4) Choke cable
2nd Check Fuel and Emission Control Systems
Engine
1) Compression
2) Overheating
Others
1) Clutch slippage
2) Brake dragging
4 A-17

4A TROUBLESHOOTING GUIDE
F6 (SINGAPORE)
The Troubleshooting Guide lists the systems most likely
to
cause
a
given symptom. After finding
the

system(s)
to
check, refer
to the
pages shown
for
detailed guides
for
each system.
POSSIBLE CAUSE
\ PAGE


SYMPTOM
Air

cleaner
(Air
cleaner
element)

Intake

air
temperature
control
system

Idle

adjustment
Fuel
system
(Carburetor,
Fuel
pump)

Air

injection
system
Deceleration
control
system
Positive
crankcase
ventilation
system

Exhaust

system

Idle-up

control
system

POSSIBLE CAUSE
\ PAGE


SYMPTOM 4A-23 4A-60 4 A—38 4A—24 4A-58 4A-45 4A-67 4A-SW 4A—68
1 Hard start
or
won't start (Cranks
OK)
1 2

2 Engine stalls During warm
up
3 2 1 4
2 Engine stalls After warm
up
3 2 4 1

3 Rough idle During warm
up
3 2 1 4
3 Rough idle After warm
up
3 2 4 1

4 High idle speed after warm
up
1 4 3* 2

5 Poor acceleration, hesitation,
or
lack
of
power
1 2 3

6 Runs rouah
on
deceleration
2 1

7 Afterburn
in
exhaust svstem
2 1

8 Poor fuel consumption
2 1 4 3

9 Fails emission test
6 4 5 3 2 1
Only MTX
76G04A-016
The numbers
of
the list show the priorities
of
inspections from the most possible to that with the lowest
possibility.
These were determined
on the
following basis:
• Ease
of
inspection
•
Most possible system
•
Most possible point
in
system
TROUBLESHOOTING PROCEDURE:
1st Check
the
following items:
Electrical system
1) Battery condition
2) Fuses
Ignition system
1) Spark plugs
2) Ignition timing
Fuel system
1) Fuel level
2) Fuel leakage
3) Fuel filter
4) Idle speed
Intake
air
system
1) Vacuum
or air
leakage
2) Vacuum hose routing
3) Accelerator cable
Engine
1) Compression
2) Overheating
Others
1) Clutch slippage
2) Brake dragging
2nd Check
the
Fuel
and
Emission Control Systems
4A—18

TROUBLESHOOTING GUIDE
4A

FE
12
VALVE and
F8
(EXCEPT MIDDLE EAST and GENERAL)
The Troubleshooting Guide lists the systems most likely to cause
a
given symptom. After finding
the

system(s)
to
check, refer
to
the pages shown
for
detailed guides
for
each system.
POSSIBLE CAUSE
\ PAGE
SYMPTOM


Air

cleaner
(Air

cleaner

element)

Intake

air

temperature

control
system

Idle

adjustment
Fuel
system
(Carburetor,
Fuel
pump)
PTC
heater
system

Air

injection
system
Positive
crankcase
ventilation
system
Deceleration
control
system

Idle-up

control
system

Ignition

control
system

POSSIBLE CAUSE
\ PAGE
SYMPTOM

4A-23 4A-60 4A-38 4A-24 4A-42 4A-58 4A-67 4A—45 4A—68 4 A—80
1 Hard start
or
won't start
(Cranks
OK)
1 2

2 Engine stalls During warm
up
5 4 1 6 2 3
2 Engine stalls After warm
up
3 2 4 1

3 Rough idle During warm
up
5 4 1 6 2 3
3 Rough idle After warm
up
3 2 4 1

4 High idle speed after warm
up
1 4 3 2

5 Poor acceleration, hesitation, or lack
of
power
1 4 2 3

6 Runs rough
on
deceleration
2 1

7 Afterburn
in
exhaust system
2 1

8 Poor fuel consumption
3 1 4 2
4
9 Fails emission test
6 2 5 3 1 4

76G04A-017
The numbers of the list show the priorities
of
inspections from the most possible to that with the lowest
possibility.
These were determined
on the
following basis:
• Ease
of
inspection
•
Most possible system
•
Most possible point
in
system
TROUBLESHOOTING PROCEDURE:
1st Check the following items:
Electrical system
1) Battery condition
2) Fuses
Ignition system
1) Spark plugs
2) Ignition timing
Fuel system
1) Fuel level
2) Fuel leakage
3) Fuel filter
4) Idle speed
Intake
air
system
1) Vacuum
or air
leakage
2) Vacuum hose routing
3) Accelerator cable
Engine
1) Compression
2) Overheating
Others
1) Clutch slippage
2) Brake dragging
2nd Check the Fuel
and
Emission Control Systems
4A—19

4A TROUBLESHOOTING GUIDE
FE and F8 (GENERAL)
The Troubleshooting Guide lists the systems most likely to cause a given symptom. After finding the
system(s) to check, refer to the pages shown for detailed guides for each system.
POSSIBLE CAUSE
\ PAGE
SYMPTOM

Air

cleaner

(Air

cleaner

element)

Intake

air

temperature

control

system

Idle

adjustment

Fuel

system

(Carburetor,

Fuel

pump)

Idle-up

control
system
PTC
heater
system
Positive
crankcase

ventilation

system

Deceleration

control
system
POSSIBLE CAUSE
\ PAGE
SYMPTOM 4A-23 4A—60 4A—38 4A—24 4A—68 4A—42 4A—67 4A—45
1 Hard start or won't start (Cranks OK) 1 2
2 Engine stalls During warm up 5 4 1 6 2 3 2 Engine stalls After warm up 3 2 4 1
3 Rough idle During warm up 5 4 1 6 2 3 3 Rough idle After warm up 3 2 4 1
4 High idle speed after warm up 1 4 2 3
5 Poor acceleration, hesitation, or lack of power 1 4 3 2
6 Runs rough on deceleration 2 1
7 Afterburn in exhaust system 2 1
8 Poor fuel consumption 2 1 3
9 Fails emission test 3 2 4 1
76G04A-018
The numbers of the list show the priorities of inspections from the most possible to that with the lowest
possibility.
These were determined on the following basis:
Ease of inspection Most possible system Most possible point in system
TROUBLESHOOTING PROCEDURE:
1st Check the following items:
Electrical system
1) Battery condition
2) Fuses
Ignition system
1) Spark plugs
2) Ignition timing
Fuel system
1) Fuel level
2) Fuel leakage
3) Fuel filter
4) Idle speed
Intake air system
1) Vacuum or air leakage
2) Vacuum hose routing
3) Accelerator cable
Engine
1) Compression
2) Overheating
Others
1) Clutch slippage
2) Brake dragging
2nd Check the Fuel and Emission Control Systems
4A—20

TROUBLESHOOTING GUIDE 4A
FE (MIDDLE EAST)
The Troubleshooting Guide lists the systems most likely to cause a given symptom. After finding the
system(s) to check, refer to pages shown for detailed guides for each system.
V. POSSIBLE CAUSE
\ PAGE
SYMPTOM

I
Air

cleaner

(Air

cleaner

element)

Intake

air

temperature

control

system

Idle

adjustment

Fuel

system

(Carburetor,

Fuel

pump)

Idle-up

control

system
Dashpot

(Only

MTX)

Positive

crankcase

ventilation

system
Exhaust
system

Evaporative

emission

control

system

Auto-return

choke

system

V. POSSIBLE CAUSE
\ PAGE
SYMPTOM 4A—23 4A-60 4 A—38 4A-24 4A-68 4A-50 4A-67 4A-96 4A-78 4A-40
1 Hard start or won't start
(Cranks OK) 1 2 3
2 Engine stalls During warm up 3 2 1 4 2 Engine stalls After warm up 3 2 4 1
3 Rough idle During warm up 3 2 1 4 3 Rough idle After warm up 3 2 4 1
4 High idle speed after warm up 1 5 3 4 2
5 Poor acceleration, hesitation, or lack of power 1 2 3
6 Runs rough on deceleration 2 1
7 Afterburn in exhaust system 3 1 2
8 Poor fuel consumption 5 1 6 2 3 4
9 Falls emission test 5 4 6 3 1 2
76G04A-019
The numbers of the list show the priorities of inspections from the most possible to that with the lowest
possibility.
These were determined on the following basis:
• Ease of inspection • Most possible system • Most possible point in system
TROUBLESHOOTING PROCEDURE:
1st Check the following items:
Electrical system
1) Battery condition
2) Fuses
Ignition system
1) Spark plugs
2) Ignition timing
Fuel system
1) Fuel level
2) Fuel leakage
3) Fuel filter
4) Idle speed
Intake air system
1) Vacuum or air leakage
2) Vacuum hose routing
3) Accelerator cable
4) Choke cable
Engine
1) Compression
2) Overheating
Others
1) Clutch slippage
2) Brake dragging
2nd Check the Fuel and Emission Control Systems
4 A—21