1953 JEEP CJ lock

FUEL
SYSTEM

14261

FIG.
E-6—CARBURETOR—
F4 ENGINE,
LATE
MODEL 1—
Choke
Clamp Bracket
2—
Throttle
Lever
and Shaft
3—
Choke
Shaft and
Lever

4—
Bowl
Vent Tube
5—
Fuel
Inlet Elbow
6—
Dash
Pot Bracket 7—
Throttle
Lever
8—
Dash
Pot Plunger
9—
Dash
Pot Assembly
10—
Lock
Nut
11— Stop Pin

1
2—Idle Mixture
Limiter
Cap
13—
Idle
Speed Adjusting Screw 14—
Fast
Idle Connecting Rod
E-11.
Float System

The
float system, Fig. E-7, consists of a float,
float
pin,
air horn gasket and the
needle
and seat assembly. These parts control the fuel level in the

carburetor
bowl, a supply being maintained for all
systems under all operating conditions. To prevent
float
vibration
from affecting the fuel level, the
inlet or float valve is spring loaded. Should the

needle
and seat
become
worn, they must be re­
placed
with a matched set, including the spring,

which
is the only way they are supplied. When
reinstalling
the float, be sure to install the float pin

with
the
stop
shoulder on the side away from the bore of the carburetor.

E-12.
Float Adjustment

Correct
float level setting is required for accurate
metering of fuel in both low- and high-speed jets.

To
set the float, remove and invert the bowl cover. Remove the bowl cover gasket. Allow the weight
of the float to rest on the
needle
and spring. Be

sure
there is no compression of the spring other

than
the weight of the float. Adjust the level by
bending the float arm lip that contacts the
needle
(not the arm) to provide specified clearance be­
tween the float and cover. The specified clearance of the float is
L74\F
[6,74 mm.] on current models
(including
Exhaust
Emission Control) and [7,93 mm.] on early models shown as A in
Fig.
E-8.
FIG.
E-7—FLOAT SYSTEM
1—
Float
and
Lever
Assembly
2—
Needle
Valve and Seat Assembly

3—
Vent

4—
Float
Bowl Cover 5—
Float
7 '.. j
io8Si
i

FIG.
E-8—FLOAT
LEVEL
GAUGING
E-13.
Low-Speed System

Fuel
for idle and early part-throttle operation is
metered through the low-speed system. The low-
speed system is illustrated in Fig.
E-9.
Liquid
fuel enters the idle well through the metering rod jet.

Low-speed
jet measures the amount of fuel for
idle and early part-throttle operation. Air-by-pass,
economizer, and idle air bleed are carefully
cali­

brated
orifices which serve to break up the liquid
fuel
and mix it with air as it
moves
through the passage to the idle port and idle adjustment screw

port.

E-14.
Idle Mixture Adjustment

Note:
The idle mixture adjustment procedure for
the late model
YF-4941S
and
YF-6115S
Carter
Carburetor
equipped with the
External
Idle

Mixture
Limiter
Cap is the same as outlined below 114

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

E

FIG.
E-9—LOW-SPEED
SYSTEM

1—
Body
Flange 6—Idle Air Bleed

2—
-Idle
Adjustment Screw Port
7—Air
By-pass
3—
Idle
Port 8—Economizer

4—
Idle
Well
9—Metering Rod Jet
5—
Low
Speed Jet 10—Idle Adjustment Screw
in
Pars.
"A"
through
"D";
however, because of the

Idle
Limiter
Cap,
the idle mixture screw
CANNOT

be adjusted in the counter-clockwise
(rich)
direc­
tion. The adjustment is made from the
rich
stop

position and the mixture screw is turned in (clock­
wise) approximately %
turn
to
"Lean
Best
Idle."
Refer
to Fig. E-6.

The
"Lean
Best
Idle"
method of idle
setting
is as
follows:

a.
Any scheduled service of ignition system should precede this adjustment.

b.
Connect tachometer or vacuum
gauge
to
engine.

c.
Warm
up
engine
and stabilize temperatures.

d.
Adjust
engine
idle to
speed
desired, using throt­tle idle
speed
adjusting screw.
e. Carburetors without Idle
Limiter
Cap
turn
idle
mixture
screws out (counterclockwise) until a
loss

of
engine
speed
is indicated; then slowly
turn
mix­
ture
screw in (clockwise
-leaner)
until maximum

speed
(RPM) is reached. Continue turning in (clockwise) until
speed
begins
to drop;
turn
mixture
adjustment back out (counterclockwise
-rich)
until
maximum
speed
is just regained at a "lean as
possible" mixture adjustment.

E-15.
High-Speed System

Fuel
for part-throttle and full-throttle operation
is supplied through the high-speed system shown

in
Fig. E-10. A metering rod and metering rod

jet
control the amount of fuel admitted through the nozzle for high-speed operation. The lower
end of the metering rod is calibrated in size to

accurately
meter the fuel required. As the rod
|
13346

FIG.
E-10—HIGH-SPEED
SYSTEM

1—Nozzle 7—Pump Diaphragm
Spring

2
—Metering
Rod 8—Diaphragm Assembly

3—
Pump
Lifter
Link
9—Chamber

4—
Metering
Rod Arm Assembly
10—Metering
Rod Jet 5—
Diaphragm
Shaft
11—Carburetor
Casting

6—
Upper
Pump Spring 12—Carburetor Bore is automatically raised and lowered in the jet,
the opening in the jet is varied in size to supply
fuel
proportionate to the requirements through the
higher
speed
and power range. The metering rod
is both mechanically and vacuum controlled and is
attached to the metering rod arm assembly.
During
part-throttle operation, vacuum in chamber

pulls
diaphragm down, holding metering arm
assembly against pump lifter
link.
Movement of the metering rod is controlled by the
pump lifter
link
which is attached to the carburetor
throttle shaft. At all
times
vacuum in the chamber
is strong
enough
to overcome the tension of pump

diaphragm
spring. Upper pump spring serves as

a
bumper upon deceleration and as a delayed
action spring upon acceleration. Under any operat­ ing condition, when the pump diaphragm spring
overcomes vacuum in the chamber, the metering

rod
will
move
toward the wide throttle (power) position.

Note:
Nozzle is pressed in and should not be
removed.

E-16.
Metering Rod Adjustment

Check
metering rod adjustment each time the

carburetor
is reassembled. Before adjustment is
made, be sure that the flat of metering rod arm
is parallel to the flat of pump lifter
link
as shown
(Fig.
E-10.).
With
the throttle valve
seated
in
car­

buretor
bore, press down on the upper end of
diaphragm
shaft until the diaphragm
bottoms

in
the vacuum chamber. The metering rod should
now
seat
on casting with the metering rod
arm
flat against the pump lifter
link.
If the meter­
ing rod
does
not
seat
on the casting (check by 115

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

E
Note:
The
Carter
YF-6115S Carburetor has a

throttle
return spring
attached
from the carburetor
main
body
to the carburetor
throttle
shaft. The

purpose
of
this
spring is to return the
throttle
to
idle
speed
position
should a linkage failure occur.

E-21.
Carburetor Disassembly

•
Refer to Fig. E-13. a. Pry pin spring and
clevis
clip
free
and
remove
fast-idle
connector
rod.
b- Remove air horn and bowl
cover
attaching
screws and lockwashers. Remove
choke
tube
clamp

assembly.

c. Remove air horn
assembly
and
gasket.

d. Remove ball check valve retainer ring. Invert the unit and tap
lightly
to
remove
ball check valve
retainer and ball check valve.
e. Loosen the screw locking the
throttle
shaft
arm to the
throttle
shaft. Remove the
throttle
shaft

arm
and
pump
connector
link.
f. Remove diaphragm
housing
screws.
Entire
as­
sembly
can now be
lifted
out of the
body.
This

assembly
can easily be
disassembled
and reas­

sembled
if necessary.
g. On early
models
carefully
remove
pump
intake strainer
housing
using tip of knife blade.
h. With the air horn in an
upside-down
position,

remove
pin and
float.
Invert the air horn and catch
needle
pin and
needle
pin spring.

i.
Remove
metering
rod jet. Remove
low-speed

jet.

FIG.
E-13—CARBURETOR

1— Choke Shaft and Lever
2— Screw
3— Choke Lever Spring
4— Screw and Washer
5— Choke Valve Screw 6— Choke Valve
7— Screw and Washer
8—
Air
Horn
9—
Needle
Seat Gasket
10—
Needle
Spring and Seat

11—Needle
Pin
12— Float Pin
13— Float
14— Gasket 15— Pump Spring
16— Metering Rod Arm
17— Pump
Link

18— Pump Spring Retainer
19— Vacuum Diaphragm Spring
20— Screw and washer
21— Diaphragm Housing
22— Diaphragm

23—Body

24— Gasket
25— Idle Port Plug
26— Throttle Body Lever and Shaft Assembly
27— Pump
Link
Connector
28— Throttle Shaft Arm 29— Screw and Washer
30— Throttle Valve
31— Throttle Valve Screw
32—
Fast
Idle Arm 33— Adjusting Screw
34— Body Flange Plug
35— Clevis
Clip

36— Idle Adjusting Screw
37— Idle Screw Spring
38—
Fast
Idle Connector Rod 39—
Pin
Spring
40—
Ball
Check Valve
41—
Ball
Check Valve Retainer Ring
42— Metering Rod Jet
43—
Low
Speed
Jet
44— Metering Rod
45— Metering Rod Spring 46—
Inner
Pump Spring
47— Pump Spring Retainer
48—
Bracket
and Clamp Assembly (Choke and Throttle) 5^—31 | 1X892
117

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

'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

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

E
E-47.
Reassembly

•
Refer to Fig. E-29.
Install
the valve gaskets, valves, valve retainer and
secure them with the valve retainer screws. Make
sure that the inlet and
outlet
valves are in their proper positions. Place the diaphragm spring re­
tainer in position on the diaphragm
pull
rod
and
install diaphragm spring. Position the
dia­

phragm assembly in pump
body
and attach the
cover to pump body, with file marks aligned, with
the six attaching screws. Do not draw the screws
up tight.
Install
rocker arm spring, rocker arm

pin
washers, rocker arm and rocker arm pin.
With

rocker
arm positioned on the diaphragm rod, draw
the six pump
body
screws up evenly and securely.
Install
the filter screen, cork gasket and sediment
bowl and secure them firmly with the thumb screw
on the bowl clamp.

E-48.
Vacuum
Pump

The
double-action fuel pump resembles two single-
action pumps placed one
above
the other. A single
fuel pump rocker arm actuates the two separate diaphragms. One diaphragm is part of the fuel
delivery pump and operates as described in Par.
E-45.
The other diaphragm is part of the vacuum
pump and operates as described here.

As
the actuating lever forces the diaphragm upward against spring pressure, air is forced through the

outlet
port
into
the
engine's
intake manifold. On
the return stroke, spring pressure forces the
dia­
phragm downward, creating a
partial
vacuum and
opening the inlet valve. In this manner, air is pumped out of the windshield wiper motor and
into

the intake manifold. When the wiper motor is shut off, manifold vacuum holds the diaphragm against its spring so that the
full
motion of the actuating
lever is not accompanied by a
complete
up-and-
down motion of the diaphragm.

When
the windshield wiper motor is turned on, but manifold vacuum is greater than the vacuum
created by the
booster
pump, air
flows
from the
wiper motor through both valves of the vacuum
booster.
As manifold vacuum drops off as a result
of the
engine
operating under low
speed
and high load, the vacuum created by the vacuum
booster

will
be greater than
engine
intake manifold vacuum

and
the pump
will
operate the wiper motor when the wiper control switch is turned on.

•
Refer to Fig. E-29. Remove the
eight
cover attaching screws and
lockwashers, and remove the cover, diaphragm

spring
and spring seat. Detach the diaphragm rod
from the rocker arm and remove the diaphragm.
The
valve assemblies are pressed
into
the cover

and
body
and lightly staked. They may be removed
with the point of a knife blade. If installing new valves be sure the inlet and
outlet
valves are
correctly positioned and stake them lightly with

a
small punch.
Assemble the vacuum pump in the reverse order
of disassembly, drawing the cover attaching screws up evenly and tightly.
E-49.
Fuel
Pump
Testing

Four
tests
are presented in following paragraphs to
test
for proper operation of the fuel pump. In addi­
tion, check the following:

a.
Check
for secure mounting of the fuel pump.

The
rocker arm may be working the entire pump
up and down, rather than just the pump
dia­

phragms.
b. Remove and clean the fuel sediment bowl.
c.
Check
all fuel lines.
E-50.
Volume
Check

To
measure fuel pump capacity (amount of fuel
delivered in a given time) disconnect the pump-to-

carburetor
line at the carburetor end. Place the

open
end of the line in a suitable container.
Start

the
engine
and operate at normal idle speed.
Delivery
should be one quart U.S. [1 ltr.] within
one minute.

E-51.
Pressure
Check

To
measure fuel pump pressure (force of fuel de­

livery)
disconnect the pump-to-carburetor line
at the carburetor end. Plug a pressure
gauge
and T-fitting
into
the
open
end of this line and
into
the

carburetor.
Start
the
engine
and operate at normal
idle speed. Pressure should be 2J4 to 3% psi.
[0,716
a
0,264
kg-cm2] at 1800 rpm. and at 16"
[406 mm.]
above
the
outlet.

E-52.
Vacuum
Check

To
measure fuel pump vacuum (pull of. the pump
at the inlet side) disconnect the pump-to-fuel-tank
line at the fuel pump. Attach a vacuum
gauge
to the fuel pump inlet.
Start
the
engine,
accelerate to
specified speed, and hold this
engine
speed
while
taking a
gauge
reading. Permissible
gauge
reading
is 8* [203 mm.] of mercury [Hg] at 1200 rpm. and
10j^'
[267 mm.] at 1800 rpm.
E-53.
Vacuum
Booster
Check

To
test
the condition of the vacuum
booster
pump,
disconnect both inlet and
outlet
lines at the pump.

Attach
a vacuum
gauge
to the windshield wiper
connection at the pump.
Start
the
engine,
accelerate
to
2000
rpm., and hold this
engine
speed
while taking a
gauge
reading. Permissible
gauge
reading
is 10* to 14" [254 a 356 cm.] of mercury [Hg].
E-54.'
FUEL
PUMP
(SINGLE-ACTION)
—
HURRICANE
F4
ENGINE
•
Early
Models.
Vehicles with electric windshield wiper motors are
equipped with a single-action fuel pump (Fig.

E-30).
The fuel pump cam lever is activated by an eccentric on the
engine
camshaft. When the
car­

buretor float
needle
valve closes, accumulation of
fuel in the pump
extends
the diaphragm spring.

This
action causes the rocker arm linkage to be­
come
inoperative until the pressure on the
dia­
phragm and spring is reduced. The fuel pump dis­
charge pressure is thus controlled by the diaphragm

spring.
This
provides a steady supply of fuel to the
carburetor
at a fairly constant pressure. 127