1953 JEEP DJ ECU

'Jeep*
UNIVERSAL
SERIES SERVICE
MANUAL

Dl
of packing are at top. Drive in a new shedder with

a
suitable punch. Stake the shedder in at least three places to secure it in position. Size the pack-
FIG.
Dl-39—INSTALLATION
OF
TIMING

CHAIN
AND
SPROCKET

1—
Camshaft
Sprocket 3—Timing
Chain

2—
Crankshaft
Sprocket 4—Timing
Marks

FIG.
Dl-40—FUEL
PUMP
ECCENTRIC
AND
DISTRIBUTOR
DRIVE GEAR
1—
Fuel
Pump
Eccentric
3—Camshaft
2—
Oil
Groove 4—Distributor Drive
Gear
ing by rotating a hammer handle, or similar smooth
tool, around it, as necessary, to obtain clearance
for the crankshaft vibration damper hub.

Dl-86.
Install
Timing
Chain
Cover

Note:
There
are five
bolts
which attach the timing

chain
cover directly to the cylinder block, and seven
bolts
which attach both the timing chain
cover and water pump to the cylinder block.

a.
If oil pump has not been removed from timing

chain
cover, remove fine slotted attaching screws,

oil
pump cover, gasket from timing chain cover. Completely pack the space around the oil pump gears with petroleum jelly.
There
must be no air
space left inside the pump. Secure oil pump cover

and
a new gasket to timing chain cover with five slotted attaching screws. Torque screws, alternately
and
evenly, 8 to 12 lb-ft [1,10 a 1,66 kg-m.].

Note:
Unless oil pump gears are packed with petro­
leum jelly, pump may not prime itself when
engine

is started.

b.
The gasket surfaces of the cylinder block and
timing chain cover must be smooth and clean. In­
stall
a new timing chain cover gasket and position

it
correctly on the cylinder block.

Note:
Two different timing chain cover gaskets
have been installed in production on V-6 engines.

At
any time the timing chain cover gasket is
replaced,
make sure the correct gasket is installed.

c.
Position timing chain cover to cylinder block.

Use
timing cover aligner and oil seal remover tool J-22248. Be certain that dowel pins
engage
dowel

pin
holes
before installing bolts.

d.
Lubricate
bolt threads before installation.
Install

the mounting
bolts
and torque 25 to 33 lb-ft. [3,5
a
4,6 kg-m.].

Note:
Some timing chain covers have two additional
bolts, one in each upper corner. If the timing chain
cover being installed on a crankcase with
these
two
holes
does
not have matching holes, the
holes

in
the crankcase must be plugged with two hex
socket screw plugs. The plug should be driven past
the face of the case to prevent interference with the timing chain cover. These
bolts
are not shown

in
Fig. Dl-41.

D1-87.
Install
Oil Pump

a.
Pack
•
oil pump gear pocket of timing chain
cover with petroleum jelly. Do not use chassis
lubricant.

b.
Install
gears so that petroleum jelly is forced
into every cavity of gear pocket and
between
the

teeth
of the gears.
Install
a new oil pump cover gasket.

Note:
Unless the pump is packed with petroleum

jelly,
it may not prime itself when the
engine
is

started.

c.
Mount oil pump cover on timing gear cover

with
five slotted attaching screws. Torque screws 101

Dl
DAUNTLESS
V-6
ENGINE

FIG.
Dl-41—WATER
PUMP
AND
TIMING CHAIN COVER BOLT LOCATION
Cover
Bolts

alternately and evenly 8 to 12 lb-ft. [1,10 a 1,66

kg-m.].

Dl-88.
Install
Crankshaft
Vibration
Damper

a.
Lubricate
the vibration damper hub
before
in­
stallation to prevent
damage
to the crankshaft
front oil seal during installation and when the

engine
is first started.
b.
Install
the vibration damper on the crankshaft.
Secure it with its attaching flat washer and screw.

Torque
the screw to a minimum of 140 lb-ft.
[19,35
kg-m.].

Dl-89.
Install
Crankshaft Pulley
Secure the crankshaft pulley to the crankshaft

vibration
damper with six screws. Torque screws 18 to 25 lb-ft. [2,5 a 3,4 kg-m.].

Dl-90.
Install
Oil
Level
Dipstick

Insert
oil level dipstick
into
the dipstick tube.

Dl-91.
Install
Oil
Pressure Sending Unit

Install
oil pressure sending unit in cylinder block.
Connect electrical wiring harness to unit.

Dl-92.
Install Starting Motor

Secure starting motor and
solenoid
assembly to
the flywheel housing and cylinder block with two attaching screws. Torque screw, which attaches this
assembly to the flywheel housing, 30 to 40 lb-ft. [4,1 a 5,5 kg-m.]. Torque screw, which attaches

bracket
to cylinder block, 10 to 12 lb-ft. [1,4 a 1,7 kg-m.].
Dl-93.
Install
Oil
Filter

Install
a new oil filter
element
at oil filter nipple,
at
left
side
of timing chain cover. Torque 10 to 15 lb-ft. [1,38 a 2,07 kg-m.].

D1-94. Install Water Pump
Be
certain that mating surfaces of the water pump

and
timing chain cover are clean.
Install
a new
gasket
on the pump flange. Secure the pump and
alternator adjustment bracket to the cover with
nine attaching bolts. Torque
bolts
6 to 8 lb-ft. [0,83 a 1,10 kg-m.]. Refer to Fig. Dl-41.

D1-9S.
Install
Cooling Fan
Secure the cooling fan, fan hub, and fan drive
pulley to the water pump shaft
flange
with four
attaching screws. Torque screws 17 to 23 lb-ft. [2,35 a 3,18 kg-m.].

Dl-96.
Install
Alternator
and Fan
Belt

Mount the alternator and bracket assembly on
right
cylinder head with two attaching screws.

Torque
screws 30 to 40 lb-ft. [4,1 a 5,5 kg-m.].

Fasten
the alternator
loosely
to its adjustment
bracket
with attaching flat washer and nut.
Install

the fan
belt
on its pulleys. Pivot the alternator
outward,
away from cylinder block, to apply fan

belt
tension. Adjust fan
belt
tension to 80 lb. [36,2 kg.];
tighten
alternator-to-adjustment bracket
nut to secure adjustment
setting.
Connect wiring
harness to alternator.

Dl-97.
Install
Fuel Pump

Install
two mounting
bolts
and new
gasket
on

flange
of fuel pump. Secure pump to timing chain cover with screws; torque screws 17 to 23 lb-ft. [2,35 a 3,8 kg-m.]. Connect
output
fuel line to
pump.

Dl-98.
Install Exhaust Manifold

Secure each of two exhaust manifolds to corre­
sponding cylinder head with five attaching screws,
and
one nut. Torque screws and nut 15 to 20 lb-ft. [2,07 a 2,8 kg-m.]. See Fig. Dl-42.

Dl-99.
Install Distributor

Insert
distributor drive gear
into
distributor mount-
FIG.
Dl-42—EXHAUST
MANIFOLD INSTALLATION

1—Torque
Bolts—15
to 20
lb-ft.
[2,07 a 2,8
kg-m.]

102

Dl

DAUNTLESS
V-6
ENGINE
e.
Connect electrical wiring harness to coolant
temperature sending unit. Connect two distributor leads to ignition coil. Connect fuel line
between

fuel pump and carburetor, vacuum
hose
between
distributor and carburetor, and crankcase vent
hose

to intake manifold
below
rear
of carburetor.
FIG.
D1-46—-INTAKE
MANIFOLD
INSTALLATION

1—Long Bolt 2—Open Bolt Hole
Dl-102.
ENGINE INSTALLATION

Install
the
engine
in the vehicle in the following
procedure listed
below:

a.
Attach suitable sling to
engine
lifting
eyes
and,
using a hoist, lift the
engine
from blocks or
engine
stand.
b. When
engine
is free of the stand lower it slowly

into
the
engine
compartment of the vehicle.

Note:
The
engine
and transmission must be lined
up to
engage
the main shaft and clutch plate spline
while sliding the
engine
rearward
into
the mounting
position.
c.
Install
and tighten up
bolts
securing
engine
to
flywheel housing.

d.
Install
and tighten front
engine
mounting bolts.

e.
Remove sling from the
engine.

I.
Connect exhaust pipes to right and
left
engine
manifolds.
g. Connect choke cable support bracket to
car­

buretor.

h.
Connect
engine
fuel
hoses
and fuel lines at right
frame
rail.

I.
Connect fuel lines.

j.
Mount
engine
starter motor assembly to
engine.
k.
Connect battery cable and wiring to
engine

starter
motor.

I.
Connect
engine
wiring harnesses to connectors
located on
engine
firewall.

Note:
On
engines
equipped with exhaust emission
control, replace the air pump, air distributor mani­
fold, and anti-backfire (gulp) valve. See Section F2.
m. Replace radiator, and secure with bolts,
n.
Replace and tighten right and
left
radiator sup­
port rods.
0. Connect upper and lower radiator
hoses
to the

engine.
p. Connect alternator wiring harness from connec­
tor at regulator,
q.
Replace air cleaner.
r.
Connect battery ground cable from the battery
to the
engine
and the
engine
ground strap,

s.
Replace the hood.

After
the
engine
is installed in the vehicle,
fill
radiator
with coolant and
engine
with oil (Refer to
Lubrication
Section B), then perform an
engine

Tune-up
and road
test
(Refer to Tune-up Sec­
tion C).

Dl-103.
FINAL IN-VEHICLE ADJUSTMENTS

a.
Clean
battery terminals and check battery.
b.
Check
ignition wires and connections.
c. Service carburetor air cleaner.

d.
Service positive crankcase ventilation valve.
e.
Check
fuel lines.
f. Gap and install new
spark
plugs.
g.
Check
distributor
points
and capacitor; replace
if
necessary.

h.
Check
ignition (distributor) timing; reset if
necessary. 1.
Check
carburetor adjustments; reset if necessary,

j.
With
engine
fully warmed up, tighten cylinder
head and manifold
bolts
and nuts to specified
torque.
Check
cylinder head
gaskets
and
bolts
for
air
or coolant leaks.

Note:
Tightness of cylinder head
bolts
should be
checked and corrected after 500 miles [800 km.]
of normal operation and again at 1000 miles [1600

km.].
k.
Check
fan belt tension; adjust if necessary.
I.
Check
for and correct any oil leak, fuel leak or
coolant leak. 104

E

FUEL
SYSTEM
Note:
Do not remove pressed-in parts such as
nozzle, pump jet, or antipercolator air bleed.

j.
Remove body flange attaching screws, body flange assembly, and gasket.

k.
Remove idle-adjustment screw, spring, idle

port
rivet, throttle lever assembly, washer, fast
idle arm, throttle plate screws, throttle plate, and throttle shaft.
1. Remove throttle shaft seal by prying out seal

retainer.

Note:
Do not remove pressed-in vacuum passage

orifice.

m.
Remove choke valve screws and choke valve.

Unhook
choke spring and slide shaft from housing,
n.
Wash all parts in carburetor cleaning solution

and
blow out passages with compressed air. Do not immerse diaphragm or seals in cleaning solution.

Inspect
all parts for wear or damage. Always use
new gaskets when reassembling.

E-22.
Carburetor
Reassembly

•
Refer to Fig. E-13.

To
expedite
reassembly, it is advisable to group all

related
parts by the circuit to which they belong.

a.
Install
throttle shaft seal and retainer in flange casting.

b.
Install
fast-idle
arm,
washer, and lever assembly
on throttle shaft. Slide shaft into place and install throttle valve.

c.
Install
idle port rivet plug and idle adjusting

screw
and spring.

d.
Attach flange assembly to body casting. Use new gasket.
e.
Install
low-speed jet assembly.
f.
Early
production models install pump intake
strainer
in pump diaphragm housing and carefully
press into recess.

Note:
If strainer is even slightly damaged, a new
one must be installed.
g.
Install
pump diaphragm assembly in diaphragm housing.
Then,
install pump diaphragm spring
(lower)
and retainer.

h.
Install
pump lifter
link,
metering rod
arm,
upper
pump spring, and retainer.

I.
Install
metering rod jet.

Note:
No gasket is used with this jet.

j.
Install
diaphragm housing attaching screws in
the diaphragm housing, making sure that the

edges
of the diaphragm are not wrinkled.
Lower

into place and tighten screws evenly and securely,
k.
Install
throttle shaft seal, dust seal washer, and
shaft seal spring.

I.
Install
pump connector
link
in the throttle arm
assembly.
Install
throttle shaft arm assembly on
throttle shaft guiding connector
link
in pump lifter

link
hole.
CAUTION:
Linkage
must not bind in any throttle
position. If binding occurs,
loosen
clamp screw in
throttle arm, adjust slightly, then retighten screw.

m.
Install
pump check disc, disc retainer, and lock

ring.

n.
Install
metering rod and pin spring. Connect
metering rod spring.
o.
Check
and if necessary correct meter ing rod adjustment. Follow procedure of
Par.
E-16.
p.
Install
needle
seat and gasket assembly, needle,
float
and
float pin. The
stop
shoulder on the float
pin
must be on the side away from the bore of
the carburetor.

q.
Set float level to specifications. Follow pro­ cedure of
Par.
E-12.

r.
Install
air horn gasket and air horn assembly.

Install
attaching screws, lock washers, and choke
tube clamp assembly. Tighten center screws first,
s. Slide choke shaft and lever assembly into place
and
connect choke lever
spring.
Install
choke valve.
Center
the valve by tapping lightly, then hold in
place with fingers when tightening screws,
t.
Install
fast-idle connector rod with
offset
portion
of rod on top and pin spring on outside.
Install
fast-idle connecting rod spring.

E-23.
Correcting Acceleration
Flat
Spot

Early
production
Carburetor
Models 938-S, 938-
SA,
938-SC

Inasmuch
as a flat
spot
on acceleration or low speed
stumble can
come
from causes other than
car­

buretor
malfunction, it is recommended that
engine

tuning be thoroughly checked before attempting
any
actual carburetor work. Make sure that
ignition, compression, and timing are correct and
that fuel pump is supplying enough gas. Also, the F-head
engine
employs a water-heated intake

manifold.
Proper vaporization of the fuel depends
on correct intake manifold temperature. Since this
temperature is controlled by the cooling system
thermostat, include an operational check of the
thermostat when diagnosing the stumble. Operating
temperatures consistently below
155°F.
can cause stumble.

If
the stumble persists, a
YF-938-S,
YF-938-SA,

or
YF-938-SC
carburetor can be converted to a
YF-938-SD
carburetor by installing Special Kit
924161, consisting of a pump discharge check
needle, a metering rod, and a metering rod jet. If this kit is installed, the pump discharge check

needle
replaces the original
ball,
weight, and re­

tainer
and the small wire-type retainer used with
the
ball
check assembly must not be reinstalled.

When
installing the kit, check the size of the pump discharge jet, No. 2, Fig. E-14.
Early
production
YF-938S
and
YF-938SA
carburetors have a .025" [0,635 mm.] jet installed. If the carburetor being
converted has a .025" jet it must be opened up to .031" [0,787 mm.] by running a No. 68
drill
through
the jet as shown in
Fig.
E-14.
The jet must be drilled
as it is a pressed in part and cannot be replaced.
Upon
completing the installation of the conversion

kit,
mark
or tag the carburetor to indicate that it
is a
YF-938SD.
118

'Jeep9
UNIVERSAL
SERIES
SERVICE
MANUAL

E
exterior moving parts of a carburetor are
often

responsible for unsatisfactory performance.
For
this

reason,
efficient carburetion depends upon careful cleaning and inspection while servicing.

a.
Thoroughly clean carburetor castings and metal
parts
in carburetor cleaning solvent.

Caution:
Accelerator pump plunger and any fiber

or
rubber parts should never be immersed in
car­

buretor
cleaner. Wash pump plunger in cleaning
solvent.

b.
Blow out all passages in the castings with com­
pressed air. Dry all parts with compressed air.

Make
sure all jets and passages are clean. Do
not use wire to clean fuel passages or air bleeds.

c.
Check
inlet valve
needle
and seat for wear. If

wear
is noted, the assembly must be replaced.

d.
Check
float hinge pin for wear and check float
for damage.

e.
Check
throttle and choke shaft bores for wear

and
out-of-round.
f. Inspect idle mixture adjustment
needles
for
burrs
or
grooves; replace if damaged.
g. Inspect cup of accelerator pump plunger; re­
place if damaged, worn, or hardened. Inspect pump

well
in bowl for wear or scoring.

h.
Check
filter screens for
dirt
or lint.
Clean,
and

if
they remain
clogged,
replace.

i.
If for any reason parts have
become
loose
or
damaged in the cluster assembly, the assembly
must be replaced.

Note:
Use ijew gaskets whenever the carburetor
is disassembled.

E-37.
Throttle Body Assembly
a.
Install
idle mixture adjustment
needles
and
springs in throttle body. Tighten finger-tight, then
unthread
one
turn
as a preliminary adjustment
setting.

Caution:
Do not force idle mixture adjustment
needles
against
seats
or damage may result.

b.
Invert
fuel bowl body and place new throttle
body gasket on bowl. Fasten throttle body to bowl
body with three screws and lockwashers; tighten

securely.

E-38.
Fuel
Bowl Body Assembly

a.
Drop steel discharge check
tall
of accelerator
pump into discharge hole.
Install
pump discharge

spring
and T-shaped retainer. Stake retainer in
place.

Note:
Top of retainer must be flush with flat

surface
of fuel bowl body.

b.
Install
two inserts in main well. Align surface
on lip of insert with flat surface in recess on top
of main well.
Install
venturi cluster with gasket,

and
tighten mounting screws evenly and securely.

Be
certain that center screw is fitted with fiber gasket, and that a special smooth shank screw is
used.
c.
Install
two main metering jets, power valve
gasket and power valve.

d.
Install
small aluminum inlet check
ball
in ac­

celerator
pump inlet at
bottom
of pump well. In­

sert
pump return spring into well, and center by
pressing spring downward with finger.

e.
Install
pump inlet screen in
bottom
of fuel

bowl.

E-39.
Air
Horn Body
Assembly

a.
Install
choke lever and collar on choke shaft.

Prong
on choke lever must face away from air

horn
body and be on top of choke trip lever.
b.
Install
choke shaft and lever assembly into the

air
horn. Choke rod
hole
in the choke lever must
face fuel inlet side of carburetor.

c.
Install
choke valve plate in choke shaft so that
letters RP
will
face upward in finished carburetor.
Install
two new valve plate attaching screws, but
do not tighten securely until valve plate is centered.

To
center choke valve plate on choke shaft, hold
choke valve tightly closed, then slide choke shaft

inward
to obtain approximately .020" [0,508 mm.]

clearance
between
choke trip lever and choke lever

and
collar assembly. Tighten choke valve screws

securely,
and stake lightly in place. Choke valve

will
be perfectly free in all positions when installed
correctly.

d.
Insert
outer accelerator pump lever and shaft as­ sembly into air horn body, with lever pointing to­

ward
choke shaft.
Install
inner pump arm, with plunger
hole
inward,
and tighten set screw securely.
Position pump plunger assembly on inner pump
arm,
with pump shaft pointing
inward,
and install

retainer.

e.
Install
needle
seat screen on inlet valve seat. In­

stall
seat and gasket in air horn body. Tighten seat
securely with a wide-blade screwdriver.
f.
Install
power piston into vacuum cavity.
Lightly
stake piston retainer washer in place. Piston should

travel
freely in cavity.
g.
Install
air horn gasket on air horn body, fitting
gasket over guide pin.

h.
Attach inlet valve
needle
to float.
Carefully

position float and insert float hinge pin. Drop tang
at
rear
of float arm downward toward air horn.

i.
Install
fuel inlet fitting, if removed.

j.
With
air horn assembly inverted, measure the distance from the air horn gasket to top of float
at toe \%£f [27,78 mm.] for standard carburetors

and
\%i [29,36 mm.] for exhaust emission control
equipped carburetors, as shown in Fig. E-23. Use
float level
gauge
J-5127-2. Bend float arm as re­

quired
to adjust float level.

k.
With
air horn body held upright, measure dis­
tance from gasket to
bottom
of float
pontoon
at outer end. Use a l7/s" [47,625 mm.] float drop

gauge.
Bend float tang, as required, to adjust float

drop.
See Fig. E-24.

I.
Carefully
place air horn body on fuel bowl
body, making certain that the accelerator pump
plunger is properly positioned in the pump well.
Lower
the cover gently, straight down; install air 123

FUEL
SYSTEM

1-5/32

133S2

FIG.
E-23—FLOAT
LEVEL
ADJUSTMENT
l—Float
Arm 2—Float Scam

horn
to fuel bowl with attaching screws. Tighten screws evenly and securely.

Note:
Longest air horn attaching screw
goes
in top
of pump housing.

m.
Install
choke rod into choke lever and fast-idle

cam.
Install
fast-idle cam screw and tighten se­

curely.
See Fig. E-25 for proper installation,
n.
Insert accelerator pump rod through outer
hole

and
into throttle lever; fasten with retainer.
A33S3

FIG. E-24—FLOAT DROP ADJUSTMENT
1—Float Tang 2—Float Drop Gauge 3—Float
E-40.
External
Carburetor
Adjustment

All
adjustments on the carburetor, except for float
adjustments, are made externally. For float level

and
drop adjustments, see
steps
j and k of Par.

E-38,
above.

E-41.
Accelerator Pump Adjustment

Unthread
curb-idle speed adjustment screw and completely
close
throttle valves in bore. Place
pump
gauge
across top of carburetor air horn ring,
as shown, with 15^" [29,369 mm.] leg of
gauge
pointing downwards, towards top of pump rod.

Lower
edge
of
gauge
leg should just touch the top
of the pump rod. Bend the pump rod, as required, to obtain the proper setting. See Fig. E-26. ]
13354

FIG.
E-25—CHOKE LINKAGE—INSTALLED VIEW 1—
Choke
Lever

2—
Trip
Lever

3—
Choke
Rod
4—
Throttle
Stop Screw 5—
Pump
Rod

13355

FIG.
E-26—ACCELERATOR
PUMP
ADJUSTMENT 1—
Pump
Gauge 2—
Pump
Rod

3—
Throttle
Shaft — Closed Position
E-42.
Curb
Idle Speed and Mixture
Adjustments

Adjust
curb idle speed adjustment screw to obtain

engine
idle speed as specified in Par. E-79. See Fig.

E-15.

When
engine
is at normal operating temperatures,

adjust
idle mixture
needle
screws to obtain smooth­
est
engine
idle; readjust idle speed if necessary.

Note:
Engine run on or "dieseling" is a condition

in
which combustion continues to take place after
the normal ignition spark from the distributor has
been shut off by turning off the ignition switch. It 124

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

E
is generally caused by excessive
engine
idle speed

in
combination with retarded ignition timing,

engine
heat soak or the use cf low octane fuel.
Should
engine
dieseling
(engine
running after ignition key is turned off) be experienced on V-6

engine
equipped vehicles, installation of Idle Stop
Valve
Kit
Part
No.
991722
will
correct the
difficulty.

E-43.
Fast
Idle Adjustment
No fast idle speed adjustment is required.
Fast

idle is controlled by the curb idle speed adjustment

screw.
If curb idle speed is correctly set and the choke rod is properly adjusted, fast idle speed
will

be correct;

E-44.
Dash Pot Adjustment —
F4
and V-6 Engine

•
Refer to
Figs.
E-27 and E-28. Before adjusting the dash pot, the
engine
idle speed

and
mixture should be correctly adjusted.
With
the

engine
idling at normal operating temperature,
adjust
the dash pot as follows:

The
dash pot adjustment is made with the throttle
set at curb idle (not fast idle). Loosen dash pot lock
nut and
turn
the dash pot assembly until dash pot
plunger contacts the throttle lever without the plunger being depressed.
Then
turn
the dash pot
assembly 2turns against the throttle lever, de­ pressing the dash pot plunger. Tighten the lock nut
securely. As a final check, open carburetor and
allow throttle to snap closed. Time dash pot delay­ ing action from the point where the throttle lever
hits the dash pot to the point where the lever
stops

moving. The dash pot should delay or cushion
closing action for two seconds by saying, "One
thousand and one, one thousand and two."
14204

FIG.
E-27—DASH
POT
ADJUSTMENT—V6
ENGINE
1—
Throttle
Lever
3—Dash Pot
2—
Plunger
4—Lock
Nut
E-45.
FUEL
PUMP
(DOUBLE-ACTION)
—

HURRICANE
F4
ENGINE

•
Early
Models

The
double-action fuel pump consists of a metal
body, a rubber diaphragm, rocker arm, valves,
FIG.
E-28—DASH
POT
ADJUSTMENT—F4
ENGINE

1—
Throttle
Lever
3—Dash Pot
2—
Plunger
4—Lock
Nut springs, gaskets, and a glass sediment bowl complete

with
strainer.
The
metal pump body provides
a
work­
ing housing for the diaphragm, lever, valves, and springs. The fuel pump is mounted on the left side
of the
engine
and is actuated by an eccentric on the
camshaft. An air
dome
is cast into the metal cover
to relieve the carburetor
needle
valve and the fuel
pump diaphragm of excessive pressure when the

carburetor
needle
valve is closed.

Tracing
pump operation from the beginning, the
camshaft eccentric forces the diaphragm up, over­
coming spring pressure.
This
action creates a
partial
vacuum
in the pump chamber.
Fuel
from the main

tank
is forced into the low-pressure pump chamber
through the open disc valve. Incoming fuel supplies
the force necessary to open the valve, which is

a
one-way check valve. As the
engine
camshaft continues to rotate, spring pressure forces the

diaphragm
downward as the pump rocker arm
follows the camshaft eccentric to its low
spot.

The
downward action of the diaphragm
closes

the intake valve and forces fuel to the carburetor

reservoir
through the pump
outlet
valve. Both intake and
outlet
valves are one-way check valves
opened and closed by fuel flow. No mechanical components are required in the control of valve
operation.

Fuel
is delivered to the carburetor only when the float
needle
is off its seat. When the fuel level in the carburetor bowl is high enough for the float to
force the
needle
against its seat, pressure backs up
to the fuel pump air
dome
and causes the diaphragm
to
stop
pumping. In this position, the pump is said
to be balanced because the pressure in the pump- to-carburetor line equals that of the diaphragm

spring.
In this way, fuel from the pump to the
carburetor
is always under pressure. The carburetor

uses
fuel, causing the float to drop and
pull
the

carburetor
needle
valve off its seat. Pressure in the pump immediately drops as fuel is delivered to the

carburetor
reservoir. Almost instantaneously the

diaphragm
again starts operating to pump more 125

FUEL
SYSTEM
|
11893

FIG.
E-29—FUEL
AND
VACUUM
PUMP—F4
ENGINE,
EARLY
MODELS

1—
Cover
Screw
2—
Lockwasher

3—
Diaphragm
Spring
4—
Spring
Seat 5—
Diaphragm
and Rod
6—
Oil
Seal 7—
Valve
Assembly
8— Body
9—
Rocker
Arm Pin Spring
10—
Fuel
Diaphragm
11—
Oil
Seal Retainer
12—
Diaphragm
and Rod 13—
Valve
Retainer
14—
Cover
15—
Gasket

16—
Screen

17—
Bow!

18—
Bail
19—
Gasket

20—
Screw
21—
Rocker
Arm Spring
22—
Link
Spacer
23—
Rocker
Arm

24—
Washer

25—
Body
fuel. The diaphragm can start and
stop
many
times
in
each mile of vehicle operation, but the pump
actuating lihkage is always in operation while the

engine
is running. The fuel pump incorporates a
pulsator and pulsator chamber to dampen the
effect

of pump pressure pulsations on the carburetor

needle
valve.
This
prevents high fuel level in the

reservoir
that would result from the
needle
being

jarred
away from its seat. Also, operating
economy
would be affected because a high fuel level usually results in an over-rich mixture.

The
actuating linkage has its own spring to ensure
continuous contact of the lever to the camshaft
eccentric.

This
fuel pump has a sediment bowl and filtering
screen which is attached to the top of the pump by
a
wire clamp and thumb nut. The screen and sedi­
ment bowl should be cleaned at least twice yearly
to prevent trouble due to a blocked screen or water
freezing. The bowl should be washed and wiped

dry
and the screen dried and then cleaned with a
stiff
brush.
When reassembling the bowl make cer­
tain
that the cork gasket is not broken; reverse it
and
position it flat on the seat, then install the
bowl and tighten the thumb nut securely. After
cleaning, start the
engine
and carefully inspect the
bowl for leakage.

E-46.
Disassembly
Remove the cover plate, gasket, and screen or
bowl clamp, sediment bowl, gasket and screen if so equipped.
Mark
the two castings with a file to
ensure positioning in the same relation upon
assembly. Remove the screws attaching the fuel cover to the pump body. Remove the cover,

diaphragm,
and spring. Remove rocker arm pin,
rocker
arm, and rocker arm spring. Remove the
valve plate screw and separate the valve plate

retainer,
valve gaskets, and valves.

Clean
all parts in cleaning solvent and blow out

with
compressed air. Valves should not be removed

from
the valve housing assembly.
Check
all parts
to see that
they
have not
been
cracked or broken
and
that screw threads have not
been
stripped or
cross threaded. Refer to Par. E-49 for fuel pump
testing. 126