1987 MAZDA 626 fuel consumption

4A TROUBLESHOOTING GUIDE
FE 8VALVE—UNLEADED FUEL
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.
V POSSIBLE CAUSE
\ PAGE
SYMPTOM
Air

cleaner

(Air

cleaner

element)

Idle

adjustment

Fuel

system
(Carburetor,

Fuel

pump)
PTC

heater

system

Air

injection
system

Positive

crankcase

ventilation

system

Deceleration

control
system
Exhaust
gas

recirculation

(EGR)
system

Exhaust

system
Intake
air

temperature

control
system

Idle-up

control

system
Purge

control

system
Auto-return
choke
system
V POSSIBLE CAUSE
\ PAGE
SYMPTOM 4A-23 4A-38 4A-24 4A—42 4A-58 4A—67 4A—45 4A-96 4A-97 4A—60 4A—68 4A--63 4A—40
1 Hard start or won't start
(Cranks OK) 1 2
2 Engine stalls During warm up 6 1 2 5 3 4 2 Engine stalls After warm up 4 2 3 1
3 Rough Idle During warm up 5 1 2 4 3 6 3 Rough Idle After warm up 4 2 3 1
4 High idle speed after warm up 1 5 4 3 2
5 Poor acceleration, hesitation, or lack of power 1 2 5 3 4
6 Runs rough on deceleratio 2 1
7 Afterburn in exhaust system 2 1
8 Poor fuel consumption 4 1 2 3 5
9 Fails emission test 5 1 6 4 3 2
76G04A-020
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
Intake air system
1) Vacuum or air leakage
2) Vacuum hose routing
3) Accelerator cable
4) Choke cable
2nd Check the Fuel and Emission Control Systems
Ignition system
1) Spark plugs
2) Ignition timing
Engine
1) Compression
2) Overheating
Fuel system
1) Fuel level
2) Fuel leakage
3) Fuel filter
4) Idle speed
Others
1) Clutch slippage
2) Brake dragging
4A-22

FUEL SYSTEM 4A
TROUBLESHOOTING
POSSIBLE CAUSE
\ PAGE Carburetor Fuel pump Separator
Two-way check valve (Except Middle East) Three-way check valve (Middle East)
SYMPTOM 4A—26 4A—35 4A—37 4A—37
1 Hard start or won't start (Cranks OK) 2 1
2 Engine stalls During warm up 2 1 2 Engine stalls After warm up 2 1
3 Rough idle During warm up 2 1 3 Rough idle After warm up 2 1
4 High idle speed after warm up 1
5 Poor acceleration, hesitation, or lack of power 2 1
6 Runs rough on deceleration 1
7 Afterburn in exhaust system 1
8 Poor fuel consumption 1 2 3
9 Fails emission test 1
76G04A-026
4A-25

4 A DECELERATION CONTROL SYSTEM
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the engine control unit
or switches.
FE 12Valve and F8 (ECE, Hong Kong and Singapore)—MTX
Possible cause
Page
Symptom

Anti-afterburn

valve
Dashpot Bypass
air
control
system
Idle

switch
main
air

bleed

control
system

Engine

control

unit

terminal
Possible cause
Page
Symptom

Anti-afterburn

valve
Dashpot Bypass
air
control
system
Idle

switch
main
air

bleed

control
system
E L M
Possible cause
Page
Symptom 4A—50 4A—50 4A—48 4A—93 4A—51 4A—88
Runs rough on deceleration 2 1 3 5 4
Afterburn in exhaust system 1 2 4 3 5 6
Poor fuel consumption 1 2 3
Fails emission test 7 6 1 2 3 4 5
High idle speed after warm up 1 2 3
Engine stalls during warm up 1
Rough idle during warm up 1
Poor acceleration, hesitation, or lack of power 1
76G04A-079
FE 12Valve and F8 (ECE, Hong Kong and Singapore)—ATX
Possible cause o> o 4-* uT u. E 3
(0 >
c k_ 3 •Q L-
2 ST c
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£ O
o w c o
• 1
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C
3 i CO V S.
v>

5 E c ® 5 »
5 w a> in m
< BO M S «T 2 B D 2N
Symptom 4A—50 4A—48 4A—51 4A—93 4A—86
Runs rough on deceleration 2 3 1 5 4
Afterburn in exhaust system 1 2 3 4 5
Poor fuel consumption 1 2
Fails emission test 7 6 2 1 3 4 5
High idle speed after warm up 1 2
Engine stall during warm up 1
Rough idle during warm up 1
Poor acceleration, hesitation, or lack of power 1
76G04A-080
4A—46

DECELERATION CONTROL SYSTEM 4 A
FE 8Valve—Unleaded Fuel
Possible cause
\Page ^s^
Symptom

Slow

fuel
cut
system
Coast
enrichment
system
Idle

switch
Anti-afterburn
valve

Bypass

air
control

system
Dashpot
(only
MTX)
Engine
control
unit

terminal

Possible cause
\Page ^s^
Symptom

Slow

fuel
cut
system
Coast
enrichment
system
Idle

switch
Anti-afterburn
valve

Bypass

air
control

system
Dashpot
(only
MTX)
A C G I
Possible cause
\Page ^s^
Symptom 4A-53 4A-54 4A-93 4A-50 4A-48 4A-50 4A—91
Runs rough on deceleration 8 6 1 7 3 4 5 2
Afterburn in exhaust system 7 3 1 4 2 5 8 6
Poor fuel consumption 2 1 6 5 4 3
High idle speed after warm up 2 1 3
Fails emission test 4 2 1 5 3 6 7 8 9
76G04A-081
FE 8Valve (General)
Possible cause main air bleed control
solenoid valve
Engine control unit terminal
Possible cause main air bleed control
solenoid valve
MTX ATX
Possible cause main air bleed control
solenoid valve
E F B 2F j 21
Page 4A—51 4A—90 4A—89
Checking order 1 2
76G04A-082
F6 (Singapore)
Possible cause
X^Page
Symptom

Dashpot

(Only

MTX)
Anti-afterburn
valve

idle

switch
L
Coasting

leaner

solenoid

valve
Engine

control

unit

terminal

Possible cause
X^Page
Symptom

Dashpot

(Only

MTX)
Anti-afterburn
valve

idle

switch
L
Coasting

leaner

solenoid

valve
B D
Possible cause
X^Page
Symptom 4A—50 4A—50 4A—93 4A—56 4A—92
High idle speed after warm up 1
Runs rough on deceleration 1 2 3
Afterburn In exhaust system 5 4 1 2 3
Fails emission test 4 1 2 3
76G04A-083
4A—47

TROUBLESHOOTING GUIDE 4B
TROUBLESHOOTING GUIDE
This troubleshooting guide shows the malfunction numbers and the symptoms of various failures.
Perform troubleshooting as described below.
Possible cause
Symptom
Input sensors and switches
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4B-16
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4B-17
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4B-18
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4B-19
0 <0 c a> 0) c a> 01
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4B-20
E a> in (0
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4B-21
Output solenoid valves
o «
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4B-22
0)
OI

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TJ
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4B-23
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4B-23
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4B-23
ffl a 3 • a>
2
a> > 10 >
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4B-24
Fault Indicated by SST
Code No. 01 08 09 10 12 14 15 17 25 26 28 34 35
Hard start or won't start
(Cranks OK)
Engine stalls
Rough
idle
While warming up
After warming up
While warming up
After warming up
High idle speed after
warming up
TROUBLESHOOTING PROCEDURE
Note
Step 1 under symptom is to quickly determine what system or unit may be at fault by use of the SST. (Self-Diagnosis Checker 49 H018 9A1)
1st:
Check input sensors and output solenoid valves with the
SST.
(Refer
to
page 4B—10.)

2nd:
Check other switches with the
SST.
(Refer
to
page 4B—26.)

3rd:
Check the following items:

11
Poor acceleration, hesita-
tion or lack of power
Runs rough on deceleration
Afterburn in exhaust system
Poor fuel consumption
Engine stalls or rough after hot starting
Electrical system
1) Battery condition
2) Fuses

Fuel system
1) Fuel level 2) Fuel leakage
3) Fuel filter 4) Idle speed

Engine
1) Compression 2) Overheating

Ignition system

1) Ignition spark 2) Ignition timing

Intake air system
1)
Air
cleaner element 2) Vacuum
or air
leakage 3) Vacuum hose routing
4) Accelerator cable

Others
1) Clutch slippage 2) Brake dragging

Fails emission test 4th:
Check Fuel and Emission Control Systems. (Refer
to
page 4B—8.)

76G04B-003
4B—7

4B FUEL SYSTEM
TROUBLESHOOTING
Check
the
condition
of
the wiring harness and connectors before checking
the
sensors
or
switches.
Possible
cause
Page

V
S E
i
o

o V)
0
e
~
0)
Ju
»
•E
<»
CL
01
3
0
<0
1
£
Oxygen

sensor

s c V
in
V

P
o E k_

•E **
l_
h
O
v
w
Water
thermo
switch

Q.
E
3 Q.
u

Injector

£ 3 3 o d
aj
Engine
con-
trol unit terminal
< £
8
<
Q. Oxygen

sensor

£ t->
0)
>
M Water
thermo
switch
3
u.
Injector
3
u. 3C
3E
3B
Symptom 4B-94 4B-99 4B—98 4B-95 48—97 4B-97 4B-49 4B-S1 4B-48 4B-90 4B-90
Hard start
or
won't start (Cranks
OK)
5 4 1 3 2

Engine While warming
up
4 3 2 1 5

stalls After warming
up
1 3 2 4

Rough Idle While warming
up
4 3 2 1

Rough Idle After warming
up
1 2 4 3

Poor acceleration, hesitation,
or

lack
of
power
1 3 4 2

Runs rough
on
deceleration
1 2

Afterburn
in
exhaust system
1 2

Poor fuel consumption
5 6 4 3 2 1

Falls emission test
1 2

Engine stalls
or
rough after
hot
starting
1 3 2

76G04B-059
4B—44

4B DECELERATION CONTROL SYSTEM
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches below.
Note
Make the system inspection first. If no problem is found, continue with the next system
inspection of the Troubleshooting Guide. (Refer to page 4B—7 and 8.)
Possible
^^ cause
Symptom
Dashpot Water thermo
sensor
Electrical signal
inspection
(Injector)
Possible
^^ cause
Symptom 4B—67 4B—97 4B-66
High idle speed after warming up 1
Runs rough on deceleration 1 3 2
Afterburn in exhaust system 1 3 2
Poor fuel consumption 1 3 2
Fails emission test 1 3 2
76G04B-090
Electrical Signal Inspection (Injector)
1. Connect the SST between the wiring harness and
engine control unit.
2. Set 3C or 3E position on the SST.
Note
3C — For No. 2 and No. 4 injectors
3E — For No. 1 and No. 3 injectors
76G04B-091
0-6V 0-20V
3. Check that the indicator lamps alternately flash at
idle.
86U04A-125
4B—66

TROUBLESHOOTING GUIDE 4C
TROUBLESHOOTING GUIDE
This troubleshooting guide shows the malfunction numbers and the symptoms of various failures.
Perform troubleshooting as described below.
Input sensors and switches
Possible cause
Page
Symptom and No. CO
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Output solenoid valve
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Fault Indicated by SST
Code No. 02 03 05 *i 08 09 11 12 *2 15 • 2 17 *2 25 26 *2 27 *2 28 • 2 34 36 • 2 41
Hard start or won't start
(Cranks OK)
Engine stalls
Rough
Idle
During warm up
After warm up
During warm up
After warm up
High idle speed after warm up
Poor acceleration, hesita-tion or lack of power
TROUBLESHOOTING PROCEDURE
Note
Code No. Is to quickly determine which system or unit may be at fault by use of the SST. (Self-Diagnosis Checker 49 H018 9A1 or Digital Code Checker 49 G018 9A0 with Adaptor harness 49 9200 180)
1st: Check input sensors and output solenoid valves with the SST. (Refer to
page
AC—11.)

2nd: Check other switches with the SST. (Refer to page AC—25.)
3rd: Check the following items:
Electrical system
1) Battery condition 2) Fuses
Runs rough on deceleration
Afterburn in exhaust
system
9
10
Poor fuel consumption
Engine stalls or runs
rough after hot starting
11
12
Knocking
Fuel system
1) Fuel level
2) Fuel leakage 3) Fuel filter 4) Idle speed (with test connec-tor grounded)
Engine
1) Compression 2) Overheating
Ignition system 1) Ignition spark
2) Ignition timing (with test connec-tor grounded)
Intake air system 1) Air cleaner element 2) Vacuum or air leakage 3) Vacuum hose routing 4) Accelerator cable
Others 1) Clutch slippage
2) Brake dragging
Fails emission test 4th: Check Fuel and Emission Control Systems. (Refer to page 4C—10.)
*1..
*2„
.Leaded fuel
.Unleaded fuel
76G04C-009
4C—9