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D
THE FUEL SYSTEM
Section D.l
REMOVING THE
FUEL T
ANK
Remove the hexagon drain plug and empty the tank.
Slacken
the two clips
on
t he filler
neck
hose and
with-
draw the filler extension.
Pull the
bose from
the
tank.
Take
out
the three
screws
and remove the
tank
filler
neck
seal
and
clamp plate.
Disconnect the
fud
pipe
at
the union and
the
fuel
gauge
cablt
from
the
tank unit,
each
on
the
right-hand
side
of the tank
.
Remove the two nuts
from
the bolts securing the
rear
of
the tank
10
the
anchorage
brackets on
the
frame and
remove
the
two bolts
with
spring
washen which
secure
the front
of
the
tank to
the
frame.
Withdraw the
rear
bolts
and distance
tubes.
Replacement
is
a reversal
of
the above instructions.
Section D.2
REMOVING THE FUEL P UM
P
Raise the hood and remove the
spare
wheel.
Remove tbe hood stowage compartment floor.
This
is
secured
by two
quick-release
screws
and
each requires
only
a
quaner-tum anti-clockwise
to
release the
CO\'er.
Disconnect the inlet
and outlet
pipe
union nuts.
Disconn«t the
earth
lead
and
the supply
lead from
the
terminals
on
the
pump.
Remove the two set screws
securing
the fuel pump
to
the bracket
on
the frame
cross-member.
Section
D.3
CO
NSTRUCTION
OF THE FUEL
PUMP
The fuel pump is
a
12-volt electric
S.U. type
LCS
and is
located dose to the: right-hand
stdc: of the
fuel
tank.
The pump
consists
of
three main
asse.
m blies
:
the body,
the
magnet assembly,
and the
contact breaker.
The body (17)
is
an
aluminium die-casting, to
which
two iden tical cover-plates
(
6
a
nd 18)
are
secured by
six
2
BA
screws with spring
washers.
Removal of the
lower
cover-plate
(18) gives
a =
to the fuel
filter (see
Fig.
0
.5), whilst the top plate
covers the
outlet
valve cage {5).
When the
outlet
vahl! cage
is
removed the
inlet valve (3)
is
revealed
. The valves consist of
thin brass
discs
which
should
be assembled smooth side
downwards.
The
o utlet
valve
can be extracted after the
spring
retaining
<:i
~lip
bas
been
dcll!cbe4. Care
should
be
taken not to distort the
circlip or the
correct
vah·e
lift
may be affected.
A
i
in.
diam.,ter
hole
connects the space between
the
valves to the pumpins
chamber,
which
is
a shallow
D .4
depression in
one face
of the body culing. This space
contains
the diaphragm
unit
(20)
v.hich is clamped
on
its
rim bet-.een
tbe
iron coil
ho~ing
(9)
and the
main
body (17).
A
bronu: rod
(10)
is screwed through the centre of the
armature, to
which
the
diaphragm
is attached, and
it
passes through tbe
magnet
core to the contact brealcer,
which
is
located at the other
"nd.
A
~-olute
spring
(22)
is interposed between
the armature
and
the end
plate
or the
coil to return
the
armature
and
diaphragm.
The magnet
consists
of a
cast-iron
pot
having an iron
cor" (23), on which
is
woun
d
a
coi
l
of
copper wire which
energizes the magnet. Between the magnet
housing and
the
armature
ar" fitted I
I
spherical-edged
rollers
(7).
These
locate
the
armature
centrally
within
tbc mago"t at
all
times,
and
allow
absolute freedom
of
movement
in
a
longitudinal direction. The
contact
breaker
consists
of a
small
bakelite moulding carrying two rockers
(I
I and 12)
which are both hinged to
the moulding
at
one end
and
are
connected
together
at the top
end by
two small
springs
arranged
to
gi•-e a 'throw-over' act ton.
A trunnion
is fitted
into
the centre
of
the
inner rocker, and
the bronze
push-
rod
(10)
connected
to tbe armature
is screwed into
this.
The
outer
rocker
(
I
I)
is
fitted with a
tungsten
point,
which
makes contact
with
a
further
tungsten point on a
spring
blade {14).
This
spring
blade
is connected
to one
end of
the
coil, and the other
end
of
the
coil is
connected
to
the
terminal (26).
In
order
to provide a good
earth
a
short
length of
flexible wire
connects
the outer
rocker
to one
or
the
screws
which hold
the bakelite
moulding.
Section
D.4
ACTI0::-1
OF THE FUEL PUMP
The act ion
of
the pump
is
as
follows.
When the pump
ts
at
rest
the outer
rocker lies in the
outer
position
and
the
tungsten
points are in
contact.
The
current passes
from the
terminal through
the
coil
back to
the
blade,
through
the
points, and
to the
earth
return,
thus energizing the magnet and
a
tt
racting
the
armature. This comes
forward,
bringing
the diaphragm
with it
and
sucking
fuel
through the
suction valve
into
the
pumping
chamber.
When
the
armature
has advanced
nearly to
th~
end or its
stroke the 'throw-over' mechan-
ism operates
and the outer
rocker flies
back,
separating
the points and
bruking
the
circuit.
The spring (22)
then pushes the armature
and
diaphragm back, forcing
fuel
through the
delivery
valve at a
rate determined by
the
requirements
of
the
engine.
As
soon
as
the armature
gets near
the
end of this stroke
the
'throw-over'
mechan-
ism
again operates, the
points again make contact, and the
cycle
of
operations
is
repeated.
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