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THE FUEL SYSTEM
D
Section
D.S
DlSMANTLDIG
AND
REASSEMBLING
THE
FUEL PUMP
When a pump
comes
in
for
reconditioning
the
first
thing
to
do
is to determine whether it
has
been
in
contact
with
gum
formation
in
the fuel. resulting
in
the
parts
in contact
with
the
fuel
becoming
coated
with a
s
ubstance
similar to
varnish.
These deposits cause the eventual
destruction
of
the neoprene
diaphragm.
The
easiest way
to identify
this
deposit
is
to smell the outlet
union
.
If
an unpleasant,
stale
smell
is no ticed
it
indicates
the
presence of gum in
the pump.
The
ordinary
sharp, acrid
smell
of
petrol
(gasoline)
denotes that
no gum
is
present.
Assuming
that
trouble
with
gum
formation is
indicated,
the whole
of
the parts coming into contact with fuel will
have to
be
dismantled.
Those
made
in
brass or
steel
should
be
boiled
in
20
per cent.
caustic soda
solution,
gjven
a
dip
in
strong nitric
acid,
and
th
en
washed in
boiling
water.
Those
made
in
aluminium should
be
well
soaked in methylated spirits and
cleaned.
5
,
To
dlsmaotle
the
pump
F1tst remove the six
bottom
cover
securing screws and
withdraw the
filter,
which may
be
found
to
be
compfetely
clogged with
gum.
Remove
the
top cover,
the
outlet valve
retaining
circljp,
and the outlet valve
disc.
Unscrew
the
valve cage
and
wittidraw the
inlet
valve
disc.
Next
undo
the
six
screws
holding
the two main
components
of the pump together.
All
the components
. of
the pump body-with
the exception
of
the washer,
but
including the pump body
itself-
should now be
cleaned to remove
all
trace
of
gum.
New
fibre washers
should
be
used on
replacement.
If
there
is no evidence of gum formation,
proceed as
follows:
first
u
ndo the
Six.
screws holdi ng
the
two parts of
the pump
together. The
action
of the
valves
can then be
checked by blowing
and
sucking
in
the inlet
u
nion to
check
the suction
valve
and in
the
outlet
union
to check
the delivery valve. In the former case
it
should be
possible to
blow freely
but not to
suck
air
back,
and
with the latter
to suck
and
not
blow.
Oean the filter in
fuel
wi
th
a
brush
and swill out
the
body of the
pump.
7
8
9
14
37021.
IS
-
- . /
20
Fig. D
.!
The rype LCS
fuel
pump
l"umponents
I.
OUtlet
union.
8.
Magnet coil.
I
S.
Inlet
union.
22.
Annature spring.
2. Rubber
ring.
9.
Iron
coil
housing.
16.
Rubber
ring.
23.
Magnet
core.
3.
Inlet valve.
10.
Bronze rod.
17.
Jlody.
24. Trunnion.
4.
Outlet valve.
I
I.
Outer
rocker.
18.
Lower
CO\i'CC·plate.
2S.
Bakelite
moulding.
s.
Outlet valve
caae.
12.
Inner
rocker.
19.
Filler.
26.
Terminal
sc:rew.
6.
Top cover-plate.
13.
Tun~ten
points.
20.
D
iaphragm.
7.
Spherical
rollers.
14.
Spring
blade.
21.
Annature.
I)
D
.5
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