1977 DATSUN PICK-UP fuel pump

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

When
throttle
valve
is

opened
fur

ther

locking
arm
is
detached
from

secondary
throttle
arm

permitting
see

ondary

system
to

start

operation

Linkage
between

primary
and

see

ondary
throttles
will
function

properly

if
distance

between
throttle
valve
and

inner
wall

of
throttle

chamber
is
74

mm

0
291
in

Adjustment
is
made

by
bending

connecting
link

I

L
l

1

4
CAl

Secondary
prm

ary
I

Jl
I

7
t
@

1
Roller

4

Adjust
plate

2

Connecting
lever

5
Throttle
c
amber

3
Return

plate
6
Throttle
valve

Fig
EF

48

Adjusting
interlock

opening

DASH
POT

1

Idling
speed
of

engine
and
mix

ture
must
be

well
tuned

up
and

engine
sufficiently
warm

2

Turn
throttle
valve

by
hand
and

read

engine
speed
when

dash

pot

just

touches

stopper
lever

3

Adjust
position
of

dash

pot
by

turning
nut

until

engine
speed
is
in
the

specified
range

Specified
engine

speed

Manual
transmission

1

900
to
2

100

rpm

Automatic
transmission

1
650
to
1

850

rpm

4

Tighten
lock

nuts

5
Make

sure
that

engine
speed

drops
smoothly
from
2

000
to
1

000

rpm
in

about
three

seconds
Engine
Fuel

Fig
EF
49

Adjusting
dash

pot

ACCELERATING
PUMP

I

Visually
inspect
accelerating

pump
cover
for

any
sign
of
fuel
leaks

2
If

fuel
leaks
are
found
check

gasket
and

replace
if

necessary

ANTI

DIESELING

SOLENOID
VALVE

If

engine
does
not

stop
when

igni

tion
switch
is
turned
off

this
indicates

that
a

striking
closed
solenoid

valve

is

shutting
off

supply
of
fuel
to

engine

If
harness
is
in

good
condition

replace
solencid
valve
as
a
unit

Notes

a

Tightening
torque
is
1

8
to
3
5

kg
m
13
to
25

ft
Ib

b

After

replacement
star

engine
and

check
to
be
sure
that
fuel
is
not

leaking
and
that
anti
dieseling

sol

noid
is
in

good
condition
B
C
D
D

CIRCUIT
WITH

FUNCTION
TEST

CONNECTOR

Caution
Do

not
attach
test
leads

of
a

circuit

tester
to
those
other

than

designated
Refer
to

Figure
EF

50

Menuel

trensmlsslon
models

I

Check
for

continuity
between
A

and
B
when

vehicle
is

brought
to
a

complete
stop
Refer
to

Figure
EF

50

B
C
D

D
circuit
is

functioning

properly
if

continuity
exists

and
volt

meter

reading
is

0
volt

d

c
in

step
2

below

If

continuity
does
not
exist

check

for

disconnected
connector
and
or

faulty
amplifier
speed
detecting

switch

or
B
C
D
D
solenoid
valve

2

Check
for

presence
of

voltage

across
A

and
B
at

a

speed
of
more

than
16

km
h

10
MPH
Refer
to

Figure
EF

50

Conduct
this

test

by
one
of
the

following
two

methods

I
Raising
up
rear
axle

housing
with

stand

2
Chassis

dynamometer
test

If
voltmeter

reading
is
0

volt
at
a

speed
of
more
than
16
km
h
10

MPH
circuit
is

functioning
prop

erly

If
voltmeter

reading
is
not
0
volt

check
for
disconnected
connector

burned
fuse

faulty
amplifier

B
C
D
D
solenoid
valve
or

speed

detecting
switch

3
If

by
above
checks

faulty
part
or

unit
is
located
it
should
be

removed

and
tested

again
If

necessary
replace

1

P4
11
0

8

l
1

Ignition
Icey

2

Fuse

3

Amplifier

4

Speed
detecting
switch

Above
10

mph
OFF

Below
10

mph
ON

5

Function
test
connector

6
B

C
D
D

solenoid
valve

EF711

Fig
EF

50

Checking
B
C
D
D
circuit
with

function
test

connector

for
manual
transmission

EF
25

Engine
Fuel

DISASSEMBLY
AND
ASSEMBLY

ff

C
oI

Q

f

@

ID
J

@
tJ

@
1
Lock
lever

2
Filter

set
screw

3

Fuel
filter

4
Fuel

nipple

5
Needle
valve

body

6
Needle
valve

7
Fuel

chamber

parts

8

Accelerating

pump
parts

9
Altitude

compensator
pipe

California
models

tng
ail

bleed

adJ

@

@1

@
A

Choke

chamber

B

Center

body

C
Throttle

chamber

I

J

@

EF725

EF30
11

High
speed
enricher
air
bleed

12
Choke

valve

13

Accelerating
pump
lever

14

Throttle
return

spring

15

Accelerating
pump
rod

16

Automatic

choke
cover

17
Automatic
choke

body
and

diaphragm
chamber

18
Richer

jet

19

Coasting
air
bleed
I

20

Primary
main

jet

21

Secondary
main

jet

22

Secondary
slow

air
bleed

23

Secondary
slow

jet

24

Plug

25
Air

bleed

26

Coasting
jet

27

Secondary
main
air

bleed

28
Power
valve

29

Primary
main
air

bleed

30

Plug

31

Primary
slow

jet

32
No
2

primary
slow

air
bleed

33

Primary
and

secondary
small

venturi

34
Venturi

stopper
screw

35
Choke

connecting
rod

36
Anti
dieseling

solenoid
valve

37
Fast

idle
cam

38

Diaphragm
chamber

parts

39
Idle

limiter

cap

40
Idle

adjust
screw

41
Idle

adjust
screw

spring

42
Throttle

adjust
screw

3

Thr9ttle

dj
t
5Crew

spring

44

Primary
and

secondary
throttle

valve

45

B
C
D
D

California

models

46
Vacuum

control
solenoid
valve

47
B
C

D
D
Non
Califomia

models

Note

Do
not
remove
the

parts

marked

with
an
asterisk

Ill

@ff

Fig
EF

62
Carburetor

part

Engine
Fuel

Disassembly

Properly
filling
wrenches
and

screwdrivers

must
be
used

on
the

nozzles
and

jets
as
well
as
on
the
screws
and

nuts
and
care
must

be

ex
ercised

not
to

damage
any

parts

2
Clean
the

carburetor

thorougWy

beiore

disassembly
3

Do
not

attempt
to
remove

any

parts
marked
with

an
asterisk

CO
in

Figures
EF
62
EF
63
EF
64

and

EF

66

Choke
chamber

parts

1

Coasting
air
bleed

adjusting
screw

2

High
speed
enricher
air
bleed

3
Choke

valve

4
AcceJera

ing
pump
lever

5
Throttle

return

spring

6

Accelerating

pump
rod

7
Automatic
choke

cover

8
Richer

jet

9
Automatic
choke

body
and

diaphragm
chamber

10

Coasting
air
bleed

I
fi

1i

8

J
@

Note
Do

not
remove
the

parts

marked
with

an
asterisk

l

EF
225

Fig
EF

63

Removing
choke
chamber

parts

EF

31

Engine
Fuel

1

l
@
Vacuum
control
solenoid

valve

2
B
C
D

D

3

Coasting
jet

4

Secondary
slow

jet

5

ptug

6
Air
bleed

1

Secondary
slow
air
bleed

8
Secondary
main
air
bleed

9
Power
valve

10

Primary
main

air
bleed

11

Weight
and
outlet
valve

12

ptug

13

Primary
slow
jet

14

Ptirnar
slow
air

bleed

15

Accelerator

pump
assembly

16

AntkUeselingsolenoid
vain

17
Fast

idle
earn

18
Chok
e

connecting
rod

19
Fast
idle
earn
shaft

20
Ventuci

stopper
screw

21

Primary
and

secondary

small
venturi
Center

body
parts

Sets

Note
Do
not
remove
the

parts

marked
with
an
asterisk

It

EF726

Fig
EF
64

Removing
jets

Float

I
i

@
i

j

1

L

4
2
V
4

S

@

c
4
6

e4
11

Qll
1D

Yr

J
1

t
t

1

lil
c
@5
1

p
u

I

r

i
r

1
CJi

U

7
to1

8rtj
lv
Ji
JlJ

if
I
1

2

3

4

4

1

4

2

4

3

44

4
5

Hi

5
Secondary
main

jet

Primary
main

jet

Float
chamber

parts

Fuel
inlet

assembly

Lock
lever

Filter
set
screw

Fuel
f1Iter

Fuel

nipple

Needle
valve

body

Needle

valve

Diaphragm
chamber

aiSembly

EF227

Fig
EF

65
Removing
float

EF

32

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

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