1977 DATSUN PICK-UP fuel type

3
Check

diaphragm
for

small
holes

carcks
or
wear

4

Check

rocker
arm
for
wear
at
the

mating
portion
with

camshaft

5

Check
rocker
arm

pin
for
wear
A

worn

pin
may
cause
oil

leakage

6
Check
all

other

components
for

any
abnormalities
and

replace
if
neces

sary

DESCRIPTION

INSPECTION

REMOVAL
AND

INSTALLATION

DESCRIPTION

The
electric
fuel

pump
is

adopted

on
air

conditioner

equipped
models
Engine
Fuel

ASSEMBLY

Reverse

the
order
of

disassembly

Closely
observe
the

following
instruc

tions

L

Use
new

gaskets

2

Lubricate
rocker
ann
rocker
arm

link
and

rocker
arm

pin
before
installa

tion
3

To
test
the

function

proceed
as

follows

Position
fuel

pump
assembly
about

I

meter
3
3
ft

above
fuel
level
of

fuel

strainer
and
connect
a

pipe
from

strainer
to
fuel

pump

Operate
rocker

arm
by
hand
If

fuel

is

drawn

up
soon
after
rocker
arm
is

released

fuel

pump
is

functioning

properly

ELECTRIC
FUEL
PUMP

CONTENTS

EF
11

EF
11

EF
12
DISASSEMBL
Y

ASSEMBL
Y

TROUBLE

DIAGNOSES
AND

CORRECTIONS
EF
12

EF
12

The
silicon
transistor

type
fuel

pump

consists
of

a
transistor
diodes
a

sole

I
Tr

lOsistor

6
Ou
tIet
valve

2

Plunger

7
Return

spring

3

Diaphragm

8
Filter

4

Diode

9

Magnet

5

Magnet
coil

10
Inlet
valve

INSPECTION

I
Disconnect
fuel
hose
at

pump

outlet

2

Connect

a
suitable
hose

approxi

mately
6

mm
0

24
in
inner

dia

meter
to

pump
outlet
ev
J

J

Note
If
diameter
is
too
small
the

following

proper
delivery

capacity

cannot
be
obtained
even
if

pump

functions

properly

EF
11
EF
13

noid
a

pump
mechanism
and
filter

parts

I
T
nsistor

2

Re
ist
f
I

3
Dinde

4

Signal
coil

5
Main
coil

6
Resistor
3

7
Zener
dlOdl

8

Resistor
2

EF719

Fig
EF
22
Construction

of
electric

fuel

pump

3

With
hose
outlet
in
a

higher
posi

tion

than

pump

operate
pump
and

check

delivery
capacity
for
more
than

15

seconds

4

The

capacity
should
be
I
400

cc

Engine
Fuel

CARBURETOR

CONTENTS

DESCRIPTION

EF
14
CHOKE
UNLOADER

EF
23

STRUCTURE
AND

OPERATION
EF
14

ELECTRIC
AUTOMATIC
CHOKE
EF

24

PRIMARY
SYSTEM

EF
15
INTERLOCK
OPENING
OF
PRIMARY
AND

SECONDARY

SYSTEM
EF
16
SECONDARY
THROTTLE
VALVE

EF
24

ANTI
DIESELING

SYSTEM
EF
17
DASH
POT

EF
25

FLOAT

SYSTEM
EF
18
ACCELERATING
PUMP

EF

25

BOOST
CONTROLLED

DECELERATION
ANTI
DIESELING
SOLENOID
VALVE

EF

25

DEVICE

B
C
D
D
EF
1B

B
C

D
D
CIRCUIT
WITH

FUNCTION

ELECTRIC

AUTOMATIC

CHOKE
EF
20
TEST

CONNECTOR

EF
25

DASH
POT
SYSTEM
EF
20

ALTITUDE
COMPENSATOR

ALTITUDE

COMPENSATOR

California
modelsl
EF

29

California

models

EF
20
MAJOR
SERVICE

OPERATION
EF

29

ADJUSTMENT
AND

INSPECTION
EF
21
REMOVAL
EF
29

CARBURETOR
IDLE
RPM
AND
DISASSEMBLY
AND
ASSEMBLY
EF

30

MIXTURE

RATIO

EF
21
CLEANING
AND

INSPECTION
EF
34

FUEL
LEVEL

EF
22
SERVICE
DATA
AND

SPECIFICATIONS
EF

35

FAST

IDLE

EF
22
TROU8LE

DIAGNOSES
AND

VACUUM
BREAK

EF
23
CORRECTIONS
EF

36

DESCRIPTION

The

carburetors
are
of

down
draft

two

barrel

types
which

produce
the

optimum
air
fuel
mixture
under

all

operating
conditions

They
present
several

distinct

features
of

importance
to
the

vehicle

owners

A

summary
of
the

features
is

as

follows

1
A

slow
economizer
to

make
a

smooth

connection
with

acceleration

or
deceleration

during
light
load

run

ning

It

also

assures
stable
low

speed

performance

2

An
idle

limiter
to

reduce
harmful

exhaust
emissions
to

a
minimum
3
A

B
C
D

D

device
for

reducing

hydrocarbon
H
C
emissions

4

An

electric
automatic

choke
to

facilitate
cold

starting
and
to
reduce

exhaust
emissions

5

An
anti

dieseling
solenoid
to

eliminate

dieseling
run

on

6
A

power
valve

or
vacuum
actu

ated
booster
to

ensure

smooth

high

speed
operation

7

The

carburetor

comes

equipped

with
dash

pot
which
ensures

smooth

deceleration

without

engine
stall

under

all

operating
conditions

8

The
hand

operated
altitude

com

pensator
is

installed
in
the
California

models

EF
14
STRUCTURE
AND

OPERATION

These

carburetors
consist
of

a

primary
system
for

normal

running

and
a

secondary

system
for
full
load

running

A

float

system
common
to
both

primary
and

secondary
systems
a
se

condary
switch

over
mechanism

an

accelerating
mechanism
etc
are

also

attached

An

anti

dieseling
solenoid
valve

and

a

power
valve
mechanism
are
also

installed

The
hand

operated
altitude

com

pensator
corrects
air

fuel
mixture

to

an

optimum
ratio

tZrJ

I
Fuel

nipple

2
Fuel
filter

3

Needle

4
Float

S

Primary
main

jet

6
Idle

adjust
screw

7
I
die
hole

8

Primary

bypass
hole

9

Primary
throttle
valve

10

Primary
altitude

compensator

pipe
California
models

11

Secondary
altitude

compensator

pipe
California
models
Engine
Fuel

jli@

I

12
Air
bleed

13
Primary
slow

jet

14

Plug

15

Primary
slow
air

bleed

6

Primary
main
air
bleed

17

Primary
air

vent

pipe

8
Primary
main
nOlzle

Note
Do

not
remove
the

parts
marked
with
an
asterisk

PRIMARY
SYSTEM

Prlmar
main
s
stem

The

primary
main

system
is
a

Stromburg

type
Fuel
flows
as
shown

in

Figure
EF
25

through
the
main

jet

mixting
with
air

which
comes
in

from

the
main

air
bleed
and

passes
through

the

emulsion
tube
and
is

pulled
out

into

the
venturi

through
the
main

nozzle

IdUns
and
slow
s
stem

During
low

engine
speed
as

shown

in

Figure
EF
25

fuel
flows

through

the
slow

jet
located
on
rear

right
side

of
main

nozzle

mixing
with
air

com

ing
from
the
1st
slow
air
bleed

again

mixing
with
air

coming
from
the
2nd

slow
air
bleed
and
then
is

pulled
out
I

III

@

19

Choke
valve

20

Primary
small
venturi

21

High
speed
enricher

air

bleed

22
Richer
nozzle

23
Richer

jet

24

Secondary
air

vent

pipe

into
the

engine
through
the
idle
hole

and

bypass
hole

Adoption
of
the

submerged

type
of

slow

jet
eliminates

such
hesitation
as

occurs
on
sudden
deceleration
of
the

vehicle

Slow
economizer

system
obtains

smooth
deceleration
at

high

speeds

Small

opening
of
the
throttle

valve

at

idling
or

partial
load

creates
a

large

vacuum

pressure
in
the
intake
mani

fld

By
this

vacuum

pressure
fuel
is

measured

through
the
slow

jet
located

behind
the
main

jet
And
air

coming

from
the
1st

slow
air

bleed
is
mixed

with

fuel
in
the

emulsion
hole

This
mixture
is

further
mixed
and

atomized
with
air

coming
from
the

2nd
slow
air

bleed
The
atomized

mixture
is

supplied
to
the

engine
from

EF15
25

Secondary
main
nozzle

26
Secondary
small
enturi

27
D
C
D
D
a

sembly

28

Secondary
throttle
valve

EF722

Fig
EF
25
Sectional
view

of
carburetor

the
idle
hole
and

bypass
hole
via
the

sow

sysem

passage

Accele

atlns
mechanism

The
carburetor
is

equipped
with
the

piston
type
accelerating
mechanism

linked
to
the

throttle
valve
When
the

primary
throttle
valve
shown
in

Figure
EF
26
is
closed
the

piston

goes
up
and

fuel
flows
from
the

float

chamber
through
the
inlet

valve
into

the

space
under
the

piston
When
the

throttle
valve
is

opened
the

piston

goes
down

opening
the
outlet
valve

and
fuel
is
forced

out
through
the

injector

Engine
Fuel

1
L

if

1

Pump
injector

2
Piston

3

Spring

4

Weight

5

Damper
spring

6
Piston
return

spring

7

Inlet
valve

8
Outlet
valve

EF023

Fig
EF
26
Acceleration

mechanism

Power

valve
mechanism

SECONDARY
SYSTEM

The

power
valve

mechanism
so

called
vacuum

piston

type
utilizes

the

vacuum
below
the
throttle
valve

When
the

throttle
valve
is

slightly

opened
during
light
load

running

high

vacuum
is

created
in

the
intake
mani

fold
This

vacuum

pulls
the

vacuum

piston
upward

against
the

spring

leaving
the

power
valve
closed
When

the
vacuum
below
the
throttle

valve
is

lowered

during
full
load
or

accelerat

ing

running
the

spring

pushes
the

vacuum

piston
downward

opening
the

power
valve
to
furnish

fuel
Secondary
main

lIYlltem

pulled
out

through
the
main

nozzle

into
the
small
venturi

Due
to
the

double
venturi

of
the

secondary
system
the

higher

velocity

air

current

passing
through
the
main

nozzle

promotes
the
fuel
atomization

The
structure
is

almost
the

same
as

the

primary
side
The

secondary
main

system
is

a

Stromburg
type

Fuel
air
mixture

produced
by
the

functions
of
the
main

jet
main
air

bleed

and
emulsion
tube
in

the
same

manner
as
in

the

primary
system
is

11
1

I

1

1

Primary
vacuum

port

2

Secondary
vacuum

port

3

Diaphragm
chamber

cover

of

Diaphragm

spring

S

Diaphragm

6

Secondary
throttle

valve

7

Primary
theo
nle

valve
lWll
I

1
11

l
v
1

Vacuum

piston

2

Power

valve

ET02
a

EF
512

Fig
EF
27
Sectional

view

of

po
r

valve

Fig
EF
28
Full
throttle
al

high
peed

EF

16

FLOAT
SYSTEM

There
IS

only
one

float
chamber

while
two
l

arburetor

systems
primary

Jnd

st
l

ondary
are

provided

Fuel
fed
from
the
fuel

pump
flows

through
the
filler
and
needle

valve
into

the
flo
t
chamber
A

constant
fuel

level

is
maintained

by
the
float
and

needle
valve

Because
of

the
inner
air

vent

type

of

the
float
chamber
ventilation
the

fuel

consumption
will
not

be
in

fluenced

by
some
dirt
accumulated
in

the
air

deaner

The
needle
valve

includes

special

hard
steel
ball

and
will
not

wear
for
all

its

considerably

long
use
Besides
the

inserrion

of
a

spring
wiU

prevent
the

flooding
at

rough
road

running

BOOST

CONTROLLED

DECELERATION
DEVICE

B
C
D
D

A

Boost
Controlled
Deceleration

Device
B

C
D

D
serves
to

reduce
the

hydrocarbons

He
emitted
from
en

gine
during
coasting

The

high
manifold
vacuum

during

coasting

prevents
the
mixture

from

complete
combustion

because
of
the

reduced
amount
of
mixture

per
cyl

inder

per
rotation

of

engine
with
the

result
that

a

large
amount
of

hydrocar

bons
is

emitted
into
tile

atmosphere

The
B

C
D
D
has
been

designed
to

correct

this

problem

It

opern
tes

as
follows

when
the

manifold

vacuum
exceeds
a

pre
Engine
Fuel

determined

value
the

B
C
D
D
intro

duces

an
additional
mixture

of

opti

mum
mixture
ratio
and

quantity
into

the

manifold

by

opening
a

separate

mixture

passage
in
the

carburetor

Complete
combustion

of
fuel
is
assist

ed

by
this
additional
mixture

and
the

amount

of
H
C

contained
in

exhaust

gases
is

dramatically
reduced

During
the

transition

period
from

coasting
to

idling
the
transmission

produces
a

signal
which
turns
on
the

vacuum
control

solenoid
valve
As
this

takes

place
the
valve
is

lifted
off
its

seat

opening
the

vacuum
chamber
to

the

atmosphere
The
mixture

control

valve
is
then

closed

returning
the

engine
to
the

predetermined
idling

speed

On
manual

transmission
models

this

system
consists

of
B
C
D
D

vacuo

urn
control

solenoid
valve

speed
de

tecting
switch
and

amplifier

On
automatic

transmission

models

it
consists

of
B
C
D
D

vacuum
con

trol

solenoid
valve

and

inhibitor

switch

B
C
D
D

operation

Diaphragm
I

Qj
monitors
the

mani

fold

vacuum
and

when
the

vacuum

exceeds
a

pre
fetermined
value
acts
so

as

to

open
the

vacuum
control
valve

@
This
causes

the
manifold

vacu
urn

to
be

introduced
into
the

second

vacuum
chamber
and

actuates
dia

phragm
ll@

When

diaphrngm
II

operates
the

mixture

control
valve

@
opens
the

passage
and
introduces
the
additional

mixture
into

the
manifold

EF

18
The
amount
of

the
mixture

is
con

trolled

by
the

servo
action

of
the

mixture
control

valve

CID
and

vacuum

control

valve

@
so

that

the
manifold

vacuum

may
be

kept
at
the

pre

determined

value

The
amount

of
mixture

depends

mainly

upon
the

coasting
air
bleed

II@
while
the
mixture
ratio

is
deter

mined

by
the

coasting
jet

@
and

coasting
air
bleed

@
See

Figure

EF
31

Vacuum

control
solenoid

valve

operation

Manual

transmission
models

The

vacuum
control

solenoid
valve

is

con
troDed

by
a

speed

detecting

switch
that
is

actuated

by
the

speed

ometer
needle

As
the
vehicle

speed
falls

below
10

MPH
this
switch
is
activated

pro

ducing
a

signal
This

signal
actuates
the

amplifier
to

open
the
vacuum
control

solenoid
valve

Automatic

transmission
models

When
the

shift
lever
is
in
N

or

P

position
the
inhibitor
switch

mounted
on
the
transmission

turns
on

to

open
the
vacuum

control
solenoid

valve

AUtomatic

trailamlsalon
modela

I

With
inhibitor

switch
ON
UN

or
P

position
check
for

presence
of

voltage
across
A
and
B
Refer
to

Figure
EF
51

If
voltmeter

ading
is

12
volts

d
c
B
C
D
O
circuit
is

func

tioning
properly

If
vol
tmeter

ading
is

zero
check

for
disconnected

connector

faulty

solenoid
valve

m
inhibitor

switch

2
With
inhibitor

switch
OFF

HI
2
IY
or
oR

position
Engine
Fuel

check

for
resistance

between
A
and
B

Refer

to

Figure
EF
51

If

ohmmeter

reading
is
25

ohms
or

below
circuit
is

functioning
prop

erly

If

ohmmeter

reading
is
32

ohms
or

above

check
for

poor
connection

of
connec
or

faulty
B
C
D
D
sole

noid
valve
or
inhibitor

relay

3

If

by
above
checks

faulty
part
or

unit
is

located
it

should
be
moved

and

tested

again
If

necessary
replace

yu
@

@
1

Ignition
key

2

Inhibit
T
switch

N
P

positions
ON

I

2
D
R

positions
OFF

3
D

C
D

D
solenoid
valve

4

Function
test
connector

5

Inhibitor

relay

EF712

Fig
EF
51

Checking
B
C

D
D
circuit
with

unction
t
st
connector

for
automatic
transmi
sion

Set

pressure

of

Boost
Controlled

Deceleration
Device
B
C
D
O

Generally
it
is

unnecessary
to
ad

just
the

B
CD
D

however
if

it
should

become

necessary
to

adjust
it
the

procedure
is
3S
follows

Prepare
the

foUowing
tool

I

Tachometer
to

measure
the
en

gine
speed
while

idling
and
a

screw

driver

2
A

vacuum

gauge
and

connecting

pipe

Note
A

quick
response

type
hoost

gauge
such
as
Bourdon
s

type
is

recommended
a

mercury
type

manometer

should
not
be
used

To

properly
set
the

B
C
D

D
set

pressure
proceed
as
follows

I
Remove

the
harness
of
solenoid

valve
To
B
D
D

solenoid
valve

1

B
C
D
D

olenoid

valve

harness

EF262

Fig
EF
52

Removing
harness

of

solenoid
valve

2

Connect
rubber
hose
between

vacuum

gauge
and
intake
manifold

as

shown

Fig
EF
53

Connecting
vacuum

gauge

EF
26
3

Warm

up
the

engine
until
it
is

heated
to

operating
temperature

Then

adjust
the

engine
at
nunnal

idling
setting
Refer
to
the

item

Idling

Adjustmenl
in

page
EF

21

Idling

engine
speed

Manual
transmission

750

rpm

Automatic
transmission

in
D

position

650

rpm

4

Run
the

engine
under
no

load

Increase

engine
speed
to
3
000
to

3
500

rpm
then

quickly
close
throttle

valve

5
At
the
time
the
manifold
vacuum

p
ssure
increases

abruptly
to

600

mmHg
23

62

inHg
or
above

and

then

graduaUy
decreases
to
the
level

set
at

idling

6
Check
that
the
B
C
D
D
set

pres

sure
is
within
the

specified
pressure

Specified

pressure
0
m
sea
level

and

760

mmHg
30

inHg
atmos

pheric

pressu

Manual
transmission

510

to
550

mmHg

20
1

to

21
7

inHg

Automatic
transmission

490
to

530

mmHg

19Tto
20

9

inHg

Notes

a
When

atmospheric
pressure
is

known

operating
pressure
will

be

found

by
tracing
the

arrow
line

A

See

Figure
EF
56

When
alti

tude
is
known

operating
pressure

will

be
found

by
tracing
the
arrow

line
B

See

Figu
EF
56

b

When

checking
the
set

pressu
of

B

CD
D
find
the

specified
set

pressu
in

Figure
EF

56
from
the

atmospheric
pressure
and
altitude

of

the

given
location

For

example
if

an
automatic
trans

mission
model
vehicle

is
located
at

an
altitude
of
1

000

m
3

280
ft

the

specified
set

p
ssu

for

B
C
D
D
is
445

mmHg
17

5

inHg

7
If
it
is

higher
than

the
set
level

turn
the

adjusting
screw
or
nut
until

correct

adjustment
is

made

Engine
Fuel

SERVICE
DATA
AND
SPECIFICATIONS

Airclelllcr

Ail
control
val

partially

opem

Air
ntrol
valve

fuUy
opens

Idle

ompensatoI

partially
opens

Hi
mettiNo

l

Bi
metal
No
2

Idle

ompen
tor

fully
opens

Bi
metal

No
1

Hi
metd
No
2

Fuels
Stem

Fuel

prtuure

Fuel

pump
apacHy

C
rbu
tor

C
rbu
tor

type

Carburetor
model
Oc

oF

oCe
F

oCe
F

Oc
OF

kpJcm2
poi

US

pt
min
at

rpm

Outlet
diameter

Venturi
diameter

Main

jet

Main
air
bleed

Slow

jet

Power
val

Float
level
U

fuel

preuure
rom
in

mm
in

mm

in

kg
cm2

psi

Adjustment

Engine
idling
Ignition
timing
Idle

speed
CO
at

mloro

Fuel
level

adjustment

Gap
between
Ive
stem
and
noat
at
mm

in

H

H

h

Fast
idle

adjwtmcnt
Fast
idle
earn

tint

step

Gap
between
throttle
IYe
and
carburetor

body

mm
in

Vacuum
break

adjustment

Gap
between
choke
alve
and
carburetor

body

mm

in

Choke
unloadel

adjusttncnt

Gap
between
choke
alw
and
carburetor

body

rom
in

Bi

metalsettinl

Bi
metal
resistance
at
2Ioe
700F

n

Bi
metalsettina

lnterloc
k

opcnina
of

primary
and

secondary

throtUc
valves
mmOn

Duh
pot

adjustment
without
loadin

I
m

Anti
diclClinasolenoid
valV
C

tiahtenina
torque

ka
m

in
lb

a
c
D
D
set

p
JSure

0
m
sea

level
and
760

mmHg

30
inlla
atmospheric
pressure
J
mmHa
inHg

R
C
D
D

tiahteninl
torque
kg
m

n
b
Nl
n
California
modell

Manual
transmiSsion

I
Automatic
transmission
California
modeb

Manual
transmission

I
Automatic
transmission

30
to
54
86
to
129

above

55
131
30
to
54
86
to
129

above
55

131

60
to
70

140
to
158

70
to
90

158
to
194
60
to
70

140
to
158

70
to
90

158
to
194

above
70

158

above
90

194
above
70

158

above
90

194

0
21
to
0
27
2
99
to
3
84

t
OOO

2
i
I
OOO
0
21
to
0
27
2
99
to

3
84

1
000
2
i
I
OOO

Strombcra
type

OCH340
7A
DCH340
48A
Stromt
rg

type

DCH34Q
45B
DCH340
46A

Primary
Secondary
Primary
Secondary
Primary
Secondary
Primary
Secondary

30
I8t

340
339
30
1
181
34
1
339
30
1
181

34
1
339
30
1

181
34
1
339

24
0
945

310
220
24
0
945
31
1
220
24
0
945
31
1
220
24
0
945
31
1
220

199
1160
199
1160
1101
1160
101

1160

170
160
170
160
170
60

170
1
60

148
1100
148
1100
148
1100
148
180

143
143
140
140

23
0
906
23
0
906
23
0
906
23

0
906

0
17
2
408
0
17
2
40B
0
17
2
408
0
17
2
408

1201750

rpm
CO

2
1
120

650

rpm
0

100
750rpm
C02
t
1
120
650

rpm
0

position
CO

2
t
1

position
CO
2
t
1

7
2

0
283
7
2
0
283
7
2
0
283
7
2
0
283

23
0
906
23

0
906
23
0
906
23
0
906

1
3
to
1
7
1

3
to

1
7
1
3
to

1
7
1
3
to
1
7

0
051
to
0
067
0
051
to
0

067
0
051
to
0
067
0
051
to
0
067

1
33
to
1
47
1
58
to
1
72
1
33
to

1
47
1
58
to
1
72

0
0524
to
0
0579
0
0622
to

0
0677
0
0524
to
0
0579
0
0622

to
0
0677

1
42
0
056
1
42
0
056
1
42
0
056
1
5
0
059

2
45
0
096
2
45
0
096
2
4
0
096
2
45
0
096

3
7
to

8
9
3
7
to
8
9
3
7
to
B
9
3
7
to
8
9

Center
of
the
ndex
mark
Center
of
the
index
mark

7
38
0
291
7
38
0

291
7
38
0

290
7
38
0
291

1
900
to

2
100
1
650
to

1
850
1
900
to
2
100
1
650
to

1
850

180
to
350

156
to
304
180
to
350

156
to
304
180
to
350

156
to

304
180
to
350

156
to
304

510
to

550
490
to

530
510
to
550
490
to
530

20
1
to
21
7
19
3
to

20
9
20
1
to
21
7
19
3

to
20
9

20
to
40

17
4
to
34
1
20

to
40

11
4
to
34
7
20
to
40

17
4
to
34
7
20
to

40
17
4
to
34
1

EF
35

DESCRIPTION

INSPECTION

CLEANING
AND
REGAP

DESCRIPTION

The

spark
plugs
are
of
the

conven

tional

type
having
14
mm
0

551
in

threads
The

spark
plug
gaps
are
1
0
to

1
1
mm
0
039
to
0
043
in
on
Cali

fomia
models
and
0
8

to
0
9
mm

0
031
to

0
035
in
on
non
California

models
The

inspection
and

cleaning

should
be
made
every
suitable
mainte

nance

period
If
necessary
replace

Note
All

spark

plugs
installed
on
an

engine
must
be

of
the
same
brand

and
the

same
number
of
heat

range

INSPECTION

L
Remove

spark
plug
wire

by

pulling
on

boot
not
on
wire
itself

2
Remove

spark
plugs

3

Check
electrodes
and
inner

and

outer

porcelains
of

plugs
noting
the

type
of

deposits
and
the

degree
of

electrode
erosion

Refer
to

Figure

EE
96

Normal
Brown
to

grayish
tan
de

posits
and

slight
electrode
wear

indicate
correct

spark
plug
heat

range

Carbon
fouled

Dry
fluffy
carbon

deposits
on
the
insulator
and

electrode
are

usually
caused

by

slow
speed
driving
in

city
weak

ignition
too
rich
fuel
mixture

dirty
air
cleaner
etc

It
is

advisable
to

replace
with

plugs

having
hotter
heat

range

Oil
fouled
Wet
black

deposits
indi

cate
excessive
oil
entrance
into

combustion
chamber

through
worn

rings
and

pistons
or
excessive
clear

ance
between
valve

guides
and

stems
If
the
same
condition
re

mains
after

repair
use
a
hotter

plug
Engine
Electrical

System

SPARK
PLUG

CONTENTS

EE
4B

EE
47

EE
47

EE
47
SERVICE
DATA
AND
SPECIFICATIONS

TROUBLE
DIAGNOSES
AND

CORRECTIONS
EE
4B

Overheating
White
or

light

gray
in

sulator
with
black
or

gray
brown

spots
and
bluish
burnt
electrodes

indicate

engine
overheating
More

over
the

appearance
results
from

incorrect

ignition
timing
loose

Normal

Overheating

EE079

4
After
cleaning
dress
electrodes

with
a
smaU
fine
file
to
flatten
the

surfaces
of
both
center
and
side

electwdes
in

parallel
Set

spark
plug

gap
to

specification

5
InstaU

spark
plugs
and

torque

each

plug
to
L5

to
2
0

kg
m

11
to
14

ft
Ib

6
Connect

spark

plug
wires

CLEANING

AND
REGAP

Clean

spark
plugs
in

a
sand
blast

type
cleaner
Avoid
excessive

blasting

Clean
and
remove
carbon
or
oxide

deposits
but
do
not

wear
away

porcelain
If

deposits
are
too
stubborn

EE
47
spark
plugs
low
fuel

pump
pres

sure

wrong
selection
of
fuel
a

hotter

plug
etc

It
is
advisable
to

replace
with

plugs

having
colder
heat

range

Ir

i

Carbon
fould

Worn

Fig
EE
96

Spark
plug

discard

plugs

After

cleaning
spark
plugs
renew

firing
surface
of
electrodes
with
me

mentioned
aboVe
Then

gap
spark

plugs
to

specified
values
with
a
round

wire
feeler

gauge
All

spark
plugs
new

or
used
should
have
the

gap
checked

and
reset

by
bending
ground
electrode

EEOBO

Fig
EE
97

Setting
park
plug
gap