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10-64
A
flexible fuel pump diaphragm is
operated by a combination of rocker
arm.action and
calibrated
spring ten-
sion.
On the
fuel intake
stroke, the cam-
shaft eccentric causes the rocker arm
to lift the fuel pump diaphragm
against
the diaphragm spring pres-
sure.
This
action draws fuel through
the
intake
valve into the pump
inlet
chamber
and
closes the outlet valve.
At
the same
time, fuel is drawn from
the fuel
tank
through the fuel intake
line to
replace
the fuel drawn into
the chamber.
As
the
camshaft eccentric con-
tinues
to
rotate,
the
rocker arm re-
lieves
the
pressure on the diaphragm
spring
and allows the spring to move
the diaphragm toward the inlet and
outlet
valves,
exerting pressure on
the fuel
inlet
chamber. This pressure
GROUP 10-
FUEL SYSTEM
causes the pump inlet valve to close
and the ensuing pressr.re build-up
opens the outlet valve. The fuel is
then forced through the pump outlet
to
-.r:.:
fuel filter where it is cleansed
before entering the carburettor. Fuel
is delivered to the carburettor
only when the fuel inlet valve in
the carburettor is open. The car-
burettor inlet valve is closed by
fuel pressure on. the float when
the specified fuel level in the
carburettor float chamber is
reached.
When there is no demand for fuel
from the carburettor, the diaphragm
spring tension is not strong enough
to force the diaphragm against the
fuel pressure built up in the inlet
chamber of the pump. Thus, the up
and down rocker arm action con-
tinues, but the diaphragm remains
EJ
REMOVAL AND INSTALLATION
fUEL FILTER REPLACEMENT
The in-line fu~·l filter (Fig.
3) is
of one-piece construction
and
cannot
be
cleaned.
Replace the filter if it
becomes clogged or restricted.
351
C.I.D. Engine
l. Remove the air
cleaner.
2. Loosen the retaining
clamp
securing the fuel inlet
hose
to
the
filter and detach the
hose from the
fllter. Discard the clamp.
3.
Unscrew
the
fuel
filter
from
the carburettor.
4
.
Screw the new filter into
the
carburettor.
5. Place a new clamp
on the fuel
inlet hose and
slide
the
hose onto the
filter.
6.
Position
the
hose clamp and
crimp securely.
7.
Start the engine and
check for
fuel leaks.
8.
Replace
the air cleaner.
302 C.I.D. Engine
l.
Remove
the
air cleaner.
2.
Hold
the
hexagonal
part of the
fllter and
unscrew
the flared
union
fuel
pipe to
filter
.
3.
Hold
the
hexagonal
female
union on the carburetor
and unscrew
the flared
union
fllter to
carburetor.
Discard
the filter.
4. Place the new filter in position
and tighten the flared union filter to
carburetor.
5. Tighten the flared union fuel
pipe to filter.
6. Start the engine and check for
fuel leaks.
7. Replace the air cleaner.
250-2V and 250 N (with air con-
ditioner) engines
1. Loosen the clamp on the by-
pass hose at the filter and detach
from filter
.
2. Hold hex part of filter to pre-
vent filter from turning and unscrew
flared union, fuel pipe to filter.
3. Hold double female adaptor and
unscrew flared union, fuel filter to
double female adaptor.
4. Remove in-line filter.
5 • Place a new filter in position and
screw top and bottom flared unions
to retain filter by holding hex. on
filter and hex on double female
adaptor, respective1y.
7. Replace the by-pass hose.
8 • Start the Engine and check for
fuel leaks.
fUEL PUMP REMOVAL
1. Disconnect the inlet line and
the outlet line at the fuel pump.
stationary until pressure against the
carburettor float is
relieved
by a de-
mand for
fuel
at
the
carburettor.
The A.C.
type and the
8
cylinder
Carter
fuel
pumps
contain
pressure·
relief orifices
in the inlet
and
outlet
valve cages
to
prevent pressure
build·
up in
the
line
to the carburettor
during hot soak periods.
The Carter
sealed fuel
pump
fitted
to 250-2V
and 250 N (with air
conditioning)
6
cylinder engines
have
an external by-pass pressure
relief.
An air vent
is
located in the fuel
pump bodies to relieve air pressure
build-up on the spring side of the
diaphragm.
The fuel pumps contain a dia-
phragm rod seal to prevent the en·
trance of engine oil into the fuel
pump.
2. Remove the fuel pump retain-
ing screws and remove the pump and
the gasket. Discard the gasket.
fUEL PUMP INSTALLATION
1.
If the fuel pump on
a 200
or
250 Six engine
is to be replaced,
transfer the fuel pump fitting(s)
to
the new fuel pump.
2. Remove all the gasket material
from the mounting pad and pump.
Apply oil-resistant sealer to both
sides of a new gasket. Position the
new gasket on the pump flange and
hold the pump in position against
the mounting pad. Make sure the
rocker ann
is
ridinc
on the camshaft
eccentric.
3. Press the pump tight
against
the pad, install the retaining screws,
and alternately torque them to speci-
fications.
4. Connect the fuel inlet line or
hose (use a new clamp on the hose)
and the outlet line. If a hose is
used
at the fuel pump connection,
crimp
the retaining clamp securely.
5. Operate the engine and check
for fuel leaks.
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