air condition DATSUN PICK-UP 1977 Owner's Guide

Engine
Fuel

TROUBLE
DIAGNOSES
AND
CORRECTIONS

Condition

Fuel

pump
fails
to

operate

Fuel

pump
fails
to

discharge
sufficient

flow

Insufficient
fuel

discharge
during

high
speed
travelling

Low
float
level

at

idling

Fuel

pump
is
actuated

more

frequently
than

under
normal
condi

tion

Rattling
noise
Probable
cause

Terminals
or
connections
loose

Rust
on
terminals
or

grounding
metal

Frozen

liquid
in

plunger
or

pump

Clogged
filter

Insufficient
fuel

Air
in

fuel
hose

through
connections

Hose
necked
down
or
bent

Fuel
tank
breather
tube
bent
or
necked

down

Weakened
return

spring

Air
sucked

through
connection
fuel
hose

and
fuel

pump
joint

Fuel
hose
on
suction
side
bent

Clogged
fIlter

Mounting
bolts
loose

EF
13
Corrective
action

Retighten

Clean

Clean

plunger
assembly

Replace
pump
if

plunger
is

stuck
or
seized

Clean

pump
interior
Clean
and

if

necessary

replace
fIlter

Replenish

Apply
a

coating
of
end
sealing

compound
to

connections
and

retighten

Check
and
correct

Check
and
correct

Replace

Apply
a

coating
of
end

sealing
compound
to

connection
and

retighten

Check
and
correct

Clean
or

replace
fIlter

Retighten

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

ELECTRIC
AUTOMATIC

CHOKE

An
electric
heater
wanns
a
bi
metal

interconnected
to
the
choke
valve
and

controls
the

position
of
choke
valve

and
throttle
valve
in
accordance
with

the

time

elapsed
the
warm

up
condi

tion

of
the

engine
and
the

outside

ambient

temperature

When
outside
ambient

temperature

is

above

operating
temperature
the

automatic

choke
control
serves
to
fur

ther
reduce
exhaust

gasemission

during
warm

up
by
automatically

selecting
one
of
the
two

choke

opera

tion
modes
fast

acting
or
slow

acting

Slow

acting
choke

operation

When
ambient

temperature
is
low

electric
current
flows

through
the

automatic

choke

relay
to
the
P
T
C

heater
A

and

gradually
warms
the

bi

metal
This
causes
the
choke
valve

to

open
slowly

Fast

acting
choke

operation

When
ambient

temperature
is

high

the
bi
metal
switch
is
in

on
This

causes
electric

current
to
flow

through

the
automatic

choke

relay
to
the

P

T
C
heater
A
and
heater

B
result

ing
in

quick

opening
of
the

choke

valve

r

@@

r

@
Engine
Fuel

The

construction
and

function
of

each

part
of

this
carburetor
are
as

follows

l
Bi
metal
and
heater
in
choke

cover

Electric
current

flows

through
the

ttea
r
as

t
le
engine
tl

1
SI
nd
war

the
bi
metal

The
deflection
of
the

bi
metal
is
transmitted
to
the
choke

valve

through
the
choke

yalve
lever

2
Fast
idle
cam

The
fast
idle

cam
determines
the

opening
of
the
throttle
valve

so
that

the

proper
amount
of

mixture
cor

responding
to
the

opening
of
the

choke
valve
will
be
obtained
The

opening
of
the

choke
valve
is

depend

ent

upon
the
warm

up
condition
of

the

engine

3

Fast
idle

adjusting
screw

This

screw

adjusts
the

opening
of

the
throttle

valve
of
the
fast

idle
earn

4
U

nloader

When

accelerating
the

engine
during

the

warm

up
period
that
is

before
the

choke

valve

opens
sufficiently
this

unloader
forces

the
choke
valve

open
a

liUle
so

as
to
obtain

an

adequate

air
fuel

mixture

5

Vacuum

diaphragm

After

the

enginThas
been

started

by
cranking
this

diaphragm
forces

the

choke
valve

open
to
the

predetermined

extent
so

as
to

provide
the

proper

air
fuel
ratio

6
Bi
metal

case
index
mark

The
bi
metal

case
index
mark
is

used

for

setting
the

moment
of
the

D

Il

EF232

1

Alternator

2
Automatic
choke

relay

3
Automatic
choke
cover

4
P

T
C
heater
A

5
Bi
metal
switch

6
P

T
C
heater
B

7
Bi
metal

8
Choke
valve

Fig
EF
33
Schematic

drawing
of
electric
automatic
choke
heater

EF

20
bi
metal
which

controls
the
air

fuel

mixture
ratio

required
for

starting

DASH
POT

SYSTEM

These
carburetors
are

equipped

with

a
dash

pot

interl
ked
wi
h

the

primary
throttle

valve

through
a
link

mechanism
The

dash

pot
is
intended

to

prevent

engine
stall

resulting
from

quick
application
of
the
brake
or

from
the

quick
release
of
the
accele
ra

tor

pedal
after

treading
it

slightly

In

such
a

situation
a
throttle
lever

strikes

against
the
dash

pot
stem
and

makes
the

primary
throttle
valve
close

gradually
thus

keeping
the

engine

running

ALTITUDE
COMPENSATOR

California
models

The

higher
the
altitude
the
richer

the
air

fuel
mixture
ratio
and
there

fore
the

higher
exhaust

gas
emissions

even

though
the

engine
is

properly
ad

justed
for
low

altitude

driving

The
altitude

compensator
is

design

ed

to
meet
EiiriSSion
S13ndards
for

driving
in
both
low
and

high
altitudes

At

high
altitudes
additional
air
is

sup

plied
to
the
carburetor

by
the
altitude

compensator
When
the
altitude

com

pensator
lever

is
set
at
H
air
is

conducted

through
an
air

passage
to

the

carburetor
The
air

passage
is

closed
when
the
lever

is
set
at
L

H

L
Lever

When

operating
the
H

L
lever
fol

low
these

instructions

H

position

Should
be
used
for

general
driving

in

those
areas

designated
by
law

as

High
Altitude
Counties

L

position

For
use
outside
those
areas

desig

nated
as

High
Altitude
Counties

Notes

a

The
idle

rpm
and
CO

vary
accord

ing
to
the
altitude
Therefore

they

should
be

properly
adjusted
when

the

position
of
the
H
L
lever
is

changed

EF729

ADJUSTMENT

AND
INSPECTION

CARBURETOR
IDLE
R
P
M

AND
MIXTURE
RATIO

Cautions

3
On

automatic
transmission

equi

ped
models
check
should
be

per

formed
in

the
0

position

Be
sure
to

engage

parking
brake
and

to
lock
both
front
and

rear
wheels

with
wheel
chocks

b

Keep
your
foot
down
on
the
brake

pedal
while

depressing
the
accelera

tor

pedal
Otherwise
vehicle

surges

forward

dangerously

Notes

a
00
not

attempt
to
screw
the
idle

adjusting
screw
down

completely

Ooing
so
could
cause

damage
to

tip

which
in
turn
will
tend
to
cause

malfunctio11ll

b
If
idle
limiter

cap
obstructs

proper

adjustment
remove
it

To
install
idle
limiter

cap
refer
to

Idle
Limiter

Cap

c
After
idle

adjustment
has
been

made
shift
the
lever
to
the
N

or

P

position
for
automatic
trans

mission

d
When

measuring
CO

percentage
in
Engine
Fuel

b
Counties
1

219
m
4
000
ft
or

more
above
sea
level
have
been

designated
by
law
as

High
Altitude

Counties
For

further
details
refer

to
1977
OATSUN
PICK
UP
Service

Bulletin
Pub
No
257

0

I
Air
cleaner

rID
mOl

If
Low
altitude

Ll

n
n

L
n

Fig
EF
34

sert

probe
into
tail

pipe
more
than

40
em

15
7
in

CO
Idle

adjustment
with

CO
meter

Idle
mixture

adjustment
requires

the
use
of
a

CO
meter

especially
for

California
models
When

preparing
to

adjust
idle
mixture
it
is

essential
to

have

the
meter

thoroughly
warmed

up

and

calibrated

I

Check
carburetor

pipes
for

proper

connection

2
Warm

up

engine
until
water

tem

perature
indicator

points
to
the
middle

of

gauge
The

procedure
to
warm

up

engine
is
not

specifically
recom

mended
Either

driving
vehicle
or

oper

ating
engine
at

no
load
will

be

good

3
Make
sure
that
water

tempera

ture
indicator

points
to
the
middle

Further

keep

engine
running
at
about

2
000

rpm
for

about
5

minutes
with

out

applying
load
to

engine
in

order
to

stabilize

engine
condition

Engine

hood
should
be

open

4
Run

engine
for
about

10
minutes

at

idling
speed
Ouring
this
10

minutes

proceed
as
described
in

steps

5

to
9
below

5
Remove
air

hose
between
3

way

connector
5

way
connector
for
Cali

fornia
models
and
air

check
valve
as

EF
21
shown
in

Figure
EF
35

Plug
the
dis

connected
hose

to

prevent
dust

from

entering

0

o

EF259

Fig
EF
35
Disconnecting
air
hose

from
air
check
valve

6
Race

engine
I
500

to
2
000

rpm

two
or
three
times

under
no
load
then

run

engine
for
one
minute
at

idling

speed

7

Adjust
throttle

adjusting
screw

until

engine
is

at

specified
speed

Engine
speed

Manual
transmission

750

rpm

Automatic
transmission

in
0

position

650

rpm

8
Check

ignition
timing
If
neces

sary
adjust
it
to

specifications

This

operation
need
not
be
carried

out
at
1

600
Ian
1

000
miles
service

Ignition
timing

Manual
transmission

120
750
rpm
Non
California

100
750

rpm
California

Automatic
transmission

in
0

position

120

650

rpm

9
At

about
10
minutes

after

engine

is
run

at

idling
speed
adjust
idle

adjusting
screw
so

that
CO

percentage

is
at

specified
level

CO

percentage

Manual
transmission

2
t
l

at
750

rpm

Automatic

transmission

in
0

position

2
t
I
at
650

rpm

10

Repeat

procedures
as
described

in

steps
6

7
and
9
above

so
that
CO

percentage
is
at

specified
level
Check

ing
idle
CO
in

step
9
can

be
carried
out

right
after

step
7

II
Race

engine

1
500
to
2

000

rpm
two
or
three

iimes
under
no

load

and
make

sure
that

specified
CO

per

centage
is
obtained

12

Connect
air

hose
to
air

check

valve

If

engine
speed
increases

readjust
it

to

the

specified
speed
with
throttle

adjustingsqew

CO
idle
edJustment
without

CO
meter

If
CO

meter
is
not

available
the

following
procedures
may
be
used

L
Check

carburetor

pipes
for

proper

connection

2
Warm

up
engine
until
water

tem

perature
indicator

points
to
the

middle

of

gauge
The

procedure
to
warm

up

engine
is
not

specifically
recom

mended
Either

driving
vehicle
or

oper

ating
engine
at

no
load
will

be

good

3
Make

sure
that

water

temperature

indicator

points
to
the
middle

Further

keep
engine
running
at
about
2

000

rpm
for
about
5

minutes
without

applying
load
to

engine
in
order

to

stabilize

engine
condition

Engine

hood
should
be

open

4
Run

engine
for

about
10
minutes

at

idling

speed

During
this

10

minutes

proceed
as

described
in

steps

5
to

9
below

5

Remove
air

hose
between
3

way

connector
5

way
connector

for
Cali

fornia
models
and
air

check
valve

shown
in

Figure
EF

35

Plug
the
dis

connected
hose

19
prevent
dust
from

entering

6
Race

engine
1
500
to
2
000

rpm

two
or

three
times
under

no
load
then

run

engine
for

one
minute

at

idling

speed

7

Adjust
throttle

adjusting
screw
so

that

engine
speeds
are

as
indicated

below

Engine
speed

Manual
transmission

815

rpm

Automatic
transmission

in
D

position

670

rpm

8
Check

ignition
timing
if
neces

sary

adjust
it

to
the
value

required
by

specifications
This

operation
need

not

be
carried
out
at
1

600
km
1

000

miles
service

9
At
about

10
minutes
after

engine
Engine
Fuel

is

run
at

idling

speed
adjust
idle

adjusting
screw
until
maximum

rpm
is

obtained

10

Repeat
procedures
as
described

in

steps
6
7
and

9
above

until

engine

speed
at
best
idle
mixture
is
815

rpm

for

manual
transmission

models
and

670

rpm
for
automatic
transmission

models

in
D

position
Adjustment

in

step
9
can
be
carried
out

right
after

step
7

11
Turn
the

idle

adjusting
screw

clockwise
until

engine
speed
drops
off

below

specified

rpm

Engine
speed

drops
off

Manual
transmission

60
to
70

rpm

Automatic
transmission

in
D

position

15
to
25

rpm

12

Connect
air
hose

to
air

check

valve

If

engine
speed
increases

readjust
it

to
the

specified

speed
with

throttle

adjusting
screw

Idle
limiter

cep

Do
not

remove
this
idle

limiter

cap

unless

necessary
If
this
unit
is
re

moved
it
must

be

readjusted
at
lime

of

installation
To

adjust
proceed
as

follows

I

After

adjusting
throttle

or
idle

speed

adjusting
screw
check

to
be
sure

that
the
amount

of
CO
contained
in

exhaust

gases
meets

the
established

standard

2

Install
idle
limiter

cap
in

position

making
sure
that
the

adjusting
screw

can
rotate
another
1
8

turn
in

the

CO

RICH
direction

Carbo
to

per

CO

rich

450
lIS
rotation

t
CO
lean

J

SQ

dl
lim

ET031
1
e
Iter

cap

Fig
EF

36

Setting
idle
limiter

cap

FUEL

LEVEL

1

Turn

down
float

chamber
to
al

low
float
to

come
into

contact
with

needle

valve
and
measure

Hu
shown

EF
22
in

Figu
re
EF

37

When
H

is

approximalely
7

mill
0
283

in

lOp
float

position
is

correct

The

top
float

position
can

be
ad

justed
by

bending
float

seat

Upon
completion
of
the

adjust

ment

check
fuel
level
wi
th

attached

level

gauge

p

j

i

I

it

I
Float
seat

2

Float

3

Float
chamber

4
Needle
valve
t
I
IIf

ET032

Fig
EF
37

Adjusting
float
level

2

Adjust
bottom
float

position
so

that
clearance
h
between

float
seat

and
needle

valve
stemis
I

3
to
L
7

mm

0
051
to
0
067
in
when

Iloat
is

fully

rals
n

Jloa
t

goppe

q
re

3

After

adjustments
in

steps
I
and

2

above
have
been
made

make
sure

that

when
fuel
is

delivered
to
the
float

chamber

the
fuel
level
is
maintained

within
the

range
of23
mm

0
91
in

as

shown
in

FigureEF
38

H
23

mm
0
91
in

EF260

Fig
EF
38

Checking
ruellevel

FAST
IDLE

I
With

carburetor

assembly
reo

moved
from

engine
measure
throttle

valve

clearance
A

with
a

wire

gauge

placing
the

upper
side

of
fast

idling

screw
on
the
first

step
on
fast

idling

cam

I

Set
circuit
tester
in
d
c

ampere

range
IA
min

fuU
scale
connect
test

probes
of
tester

as
shown
in

Figure

EF
58

Do
not
confuse

positive
line
with

negative
line

2
Turn

ignition
key
to

ON

posi

tion

I

t

EF264

1

Ignition
key

2

Amplifier

3

Speed
detecting
switch

4
B
C
D
D
solenoid
valve

Inhibitor

switch

Automatic

transmission

models

Refer
to
the
AT
section

Inhibitor

relay

Automatic
transmission

models

Inhibitor

relay

EF724

Fig
EF
59
Location
of
inhibitor

relay

2
Make

an
inhibitor

relay
check
as

shown
in

Figure
EF
60

Apply
12
volts
d
c
across
termi

nals
1

and
4

to
ensure
that

continuity

exists
between
terminals
2
and
3

Check
that

continuity
does
not

exist
between
terminals
2
and
3
when

no
voltage
is

applied
across
them
Engine
Fuel

3

Ensure
that
tester

pointer
deflects

when

ignition
key
is
turned
on

4
If
tester

pointer
does
not

deflect

when
solenoid
valve
and

speed
detect

ing
switch
circuits
are

functioning

properly
amplifier
is

faulty

Fig
EF
58

Checking
amplifier

If
results
satisfy
the
above

inhi

bitor

relay
is

functioning

properly
if

not

replace
inhibitor

relay

it
@

j
l

j
4

L
I

44
11

oJ

EF287

Fig
EF

60
Checking
inhibitor

relay

ALTITUDE

COMPENSATOR

California
models

Make
sure

that
altitude
com

pensator
to
carburetor

hoses
are
con

nected

properly
and
that

they
are
not

cracked
and
obstructed

2
Check
that
altitude

compensator

is

properly
set

At
low
altitudes

At

high
altitudes

Notes

a
The
idle

Pm
and
CO

vary
accord

ing
to
the
altitude
Therefore

they

should
be

properly
adjusted
when

the

position
of
the
H
L
lever
is

changed
Close

Open

EF
29
b
Counties
1

219
m
4
000

ft
or

more
above
sea
level
have
been

designated
by
law
as

High
Altitude

Counties
For
further
details
refer

to

1977
DATSUN
PICK
UP
Service

BuUetin
Pub
No
257

Q0

1
v

EF733

Fig
EF
61

Checking
altitude

compensator

MAJOR
SERVICE

OPERATION

The

perfectly
adjusted
carburetor

delivers
the

proper
fuel

and
air
ratios

at
all

speeds
for
the

particular
engine

for
which
it

was

designed
By
com

pletely
disassembling
which
will
allow

deaning
of
all

parts
and

passages
the

carburetor
can
be

maintained
its

origi

nal
condition
and
will
continue

to

deliver
the

proper
ratios

To
maintain

accurate
carburetion

of

passages
and

discharge
holes

ex

treme
care
must
be
taken
in

cleaning

Use

only
carburetor
solvent
and

compressed
air

to
clean
all

passages

and

discharge
holes
Never
use
wire
or

other

pointed
instrument

to
clean
or

carburetor
calibration
will
be
affected

REMOVAL

Remove
carburetor
from

engine

taking
sufficient
care
to

the

following

Precautions

a
When

disconnecting
fuel
lines
do

not

spill
fuel
from
fuel

pipe

b
When

removing
carburetor
do
not

drop
any
nut

or
bolt
into
intake

manifold

c
Be
careful
not
to
bend
or
scratch

any
part

CLEANING
AND

INSPECTION

Dirt

gum
wuler
or
l
arbon
con

taminatiun
in

or
on
exterior

moving

parts
of
a

arburctor
arc
often

respon

sihk
for

unsatisfactory
performance

For
this

reason
efficient
carbutetioll

dcpends
upon
careful

cleaning
and

inspection
while

servicing

I

Blow
all

passages
and

castings

with

compressed
air

and
blow
off
all

parts
until

dry

Note
Do
not

pass
drills

or
wires

through
calibrated

jet
or

passaaa

as
this

may
enlarge
orirlce
and

seriously
affect
carburetor
calibrs

lion

2

Check
all

parts
for
wear
If
wear

is

noted
damaged

parts
must
be
re

placed
Note

especially
the

following
Engine
Fuel

I
Check
float
needle

and
seat
for

wear
If
wear
is

noted

assembly
must

be

replaced

2
Check
throule
and
choke
shaft

bores
in
throtlle
chamber
and
choice

chamber
for
wear
or

out
of
roundness

3
Inspect
idle

adjusting
needle
for

burrs
or

ridges
Such
a

condition
re

quires
replacemen
1

3

Inspect
gaskets
0
see
if

they

appear
hard
or
briUle
or

if

edges
are

torn
or
distorted
If

any
such
condi

tion
i
noted

they
must
be

replaced

4
Check
filter
screen
for
dirt
or
lint

Clean
and
if
screen
is
distorted
or

remain

plugged
replace

5
Check

linkage
for

operating

condition

6

Inspect
operation
of

accelerating

pump
Pour
f
el
into

jloat
chamber

and
make
throtlle
lever

operate
Check

condition
of
fuel

injection
from

the

EF
34
accelerating
nowe

7

Push
connecting
rod

of
dia

phragm
chamber
and
block

passage
of

vacuum
with

finger
When

connecting

rod
becomes
free
check
for

leakage
of

air

or

damage
to

diaphragm

Jets

Carburetor

performance
depends

on

jet
and
air
bleed
That
is

why

these

components
must
be

fabricated

with
utmost
care
To

clean
them

use

cleaning
solvent
and
blow
air

on
them

Larger
inner
numbers

tamped
on
the

jet
indicate

larger
diameters
Ac

cordingly
main
and

slow

jets
with

lalger
nUmbers

provide
richer
mixture

the
smaller
the
numbers
the
leaner
the

mixture
Conversely
the
main
and

slow
air
bleeds

through
which
air
to

passes
through
make
the
fueLleaner
if

they
bear

larger
numbers
the
smaller

the
numbers

the
richer

the
fuel

Engine
Fuel

toms
and

causes
of
carburetor
troubles

and

remedies
for
them

are
listed
to

facilitate

quick
repairs

There
are
various
causes
of

engine

malfunctions
It
sometimes

happens

that
a
carburetor
which
has
no
fault
TROUBLE

DIAGNOSES
AND

CORRECTIONS

In
the

following
table
the

syml

Condition

Probable
cause

Overflow
Dirt
accumulated
on

needle
valve

Fuel

pump
pressure
too

high

Needle
valve

improperly
seated

Excessive
fuel

consumption
Fuel
overflow

Slow

jet
too

large
on
each
main

jet

Main
air
bleed

clogged

Choke
valve
does
not

open

fully

Outlet
valve
seat
of
accelerator

pump

improper

Linked

opening
of

secondary
throttle
valve

opens
too

early

Power

shortage
Main

jets
clogged

Every
throttle
valve
does
not

open
fully

Idling

adjustment
incorrect

FIICI
tr

clogged

Vacuum

jet

clogged

Air

c1eane

clogged

Diaphragm
damaged

Power
valve

operating
improperly

Altitude

compensator
setting
incorrect
Cali

fornia

models

Improper
idling
Slow

jet
clogged

Every
throttle

valve
does
not
close

Secondary
throttle
valve

operating
im

properly

Throttle
valve

shafts
worn

Packing
between

manifold
carburetor

fauJiy

Manifold
carburetor

tightening
improper

Fuel
overflow

B

C
D
D

adjustment
incorrect

Vacuum
control
solenoid

damaged

Stuck
anti
stall
dash

pot

EF

36
appears
to
have

some

problems
when

actually
the

electric

system
is
at
fault

Therefore
whenever

the

engine
is

mal

functioning
the
electrical

system

should
be
checked
rust
before

adjust

ing
carburetor

Corrective
action

Clean
needle
valve

Repair
pump

Re

place

See
condition
overflow

Replace

Clean

Adjust

Lap

Adjust

Clean

Adjust

AdjusL

pa
ir

Clean

Clean

Replace

Adjust

Correct
H
L
lever

position

Clean

Adjust

Overhaul
and

clean

Replace

Replace
packing

Correct

tightening

See
l
ondition
ov

rl1ow

Adjust

Replace

Replace

There
are
three

types
of
control

system
These
are

J

Closed

type
CIllnkcase
emission

control

system
Emission
Control

System

of

GENERAL

DESCRIPTION

2

Exhaust
emission

control

system

3

Evaporative
ell
lhsion

control

sys

tem

Pericxiic

inspection
and

required
seCV1Clng
of
these

systems
should
be

carried
out

to
reduce

harmful
emis

sions
to
a
minimum

CRANKCASE
EMISSION
CONTROL

SYSTEM

c

01

Lkf

If
1

TIL
II
tll

1

j

GUuuu
DESCRIPTION

This

system
returns

blow

by
gas
to

both
the
intake
manifold
and
carbure

tor
air

cleaner

The

positive
crankcase
ventilation

p
C
V

valve
is

provided
to
conduct

crankcase
blow
by

gas
to
the
intake

manifold

During

partial
throttle

operation
of

the

engine
the
intake
manifold
sucks

the
blow

by
gas
through
the
P
C
V

valve

Normally
the

capacity
of
the

valve

is

sufficient
to
handle

any
blow

by
and

a
small
amount
of

ventilating
air

4

c
Fresh
air

Blow
by

gas
The

ventilating
air

is
then

drawn

from

the
dust
side
of
the
cadlUretor

air
cleaner

tluough
the
tube

con

necting
carburetor
air
cleaner
to
rock

er
cover
into
the

crankcase

Under
full
tluottle

condition
the

manifold
vacuwn
is

insufficient
to

draw

the
blow

by
flow

tluough
the

valve
and
its

flow

goes
through
the

tube
connection
in
the

reverse
diree

tion

On
vehicles
with
an

excessively

high

blow

by
some
of
the
flow
will

go

through
the
tube

connection
to

carbu

retor
air
cleaner
under
all
conditions

1

Sealtypc
oil
level

gauge

2
Bame

plate

3
Flame
arrester

4
Filler

5
P
C
Y
valve

6
Steel
net

7
Bame

plate

EC716

Fig
EC

l
Crankcase
miaion
control

ay
tem

EC

2
INSPECTION

P
c
V
VALVE
AND

FILTER

Checking
P
C
V
valve
in

accord

ance

with
the

following
method

With

engine
running
at
idle

remove

the

ventilator
hose
from
P

C
V
valve

if
the

valve
is

working
a

hissing
noise

will
be
heard
as
air

passes

through
the

valve

and
a

strong
vacuwn
should
be

felt

immediately
when
a

fmger
is

placed
over
valve
inlet

Replace
P
C
V
valve
and

filter
in

accordance
with
the
maintenance

schedule

VENTILATION
HOSE

1

Check
hoses
and

hose
connec

tions
for
leaks

2
Disconnect
all
hoses

and
clean

with

compressed
air

If

any
hose
cannot
be
free
of

obstructions

replace

Ensure
that
flame
arrester

is

surely

inserted
in

hose
between
air
cleaner

and
rocker
cover

Emission
Control

System

EARLY

FUEL

EVAPORATIVE

SYSTEM
E

F
E

DESCRIPTION
spring
and

counterweight
which
are

assembled
on
the

valve
shaft

projecting

to
the

rear
outside
of
the
exhaust

manifold
The

counterweight
is
se

cured
to
the
valve
shaft
with

key
bolt

and

snap
ring
EC
4
A

control
valve
welded
to

the

valve
shaft
is

wtalled
on
the

exhaust

manifold

through

bushing
This
con

trol

valve
is

called
Heat

control

valve
The
heat
control

valve
is

ac

luated

by
the

coil

spring
thermostat
Construction
of
the

early
fuel

evap

orative

system
is

shown
in

Figure

r
I

1

@

rW

9

Sc
w

10
Thennostat

spring

11

Coil
spriiig

12
Control
valve
shaft

13
Heat
control

valve

14

Bushing

15

Cap

16
Exhaust
manifold
1
Intake
manifold

2
Stove

gasket

ManifoktstOve

4
Heat
shield

plate

5

Snap
ring

6

Counterweight

7

Key

g

Stoppel
pin

EC532

Fig
EC
4
Early
Fuel

Evaporutive
tem
E
F
E

The

early
fuel

evaporative
system
is

provided
with
a
chamber
above

a

manifold
stove
moonted
between
the

intake
and
exhaust

manifolds

During

engine

warming
up
air
fuel
mixture
in

the

carburetor
is

heated
in
the
cham

bet

by
exhaust

gases
This
results
in

improved
evaporation
of

atomized
fuel

droplets
in
the
mixture
and
in

smaller

content
of

hydrocarbons
He
in
the

exhaust

gas
especially
in

cold
weather

operation

The
exhaust

gas
flow
from
the

engine
is

obstructed

by
the
heat
con

trol

valve
in
the

exhaust
manifold
and
is

changed
in

direction
as
shown

by

the
solid

lines
in

Figure
EC
4
The

exhaust

gas
heats
the
manifold
stove

Open
close

operation
of
the

heat

control
valve
is
controlled

by
the

counterweight
and
thermostat

spring

which
is
sensitive
to
the

ambient
tem

perature
around
the

exhaust
manifold
With
this
condition
the

heat
control

valve
is
in

the

fully
closed

position

obstructing
the
flow
of

exhaust

gas
As

engine
tempera
lure

goes
up
and

the

ambient

temperature
becomes

high

enough
to
actuate
the
thermostat

spring
the

counterweight
begins
to

rotate
clockwise
and

again
comes
into

con

tact
with

the

stopper
pin
With
this

condition
the

heat
control
valve
is
in

the
full

open
position
and
exhaust

gas

passes
through
the
exhaust
manifold
as

shown

by
the
dotted

lines
in

Figure

EC
4
without
heati

ng
the
manifold

stove
OPERATION

The

counterweight
rotates
counter

clockwise
and

stops
at

the

stopper
pin

mounted
on
the
exhaust

manifold

while

the

engine
temperature
is
low

EC
6