FUEL
SYSTEM
The diesel fuel system provides a means
of
filtering,
transporting and delivering fuel
in
a fine spray to the
engine cylinder
at
the correct time
for
ignition.
The
system consists
of
a
primary fuel filter, fuel transfer
pump,
secondary fuel filter, injection pump
and
an
injection nozzle. See Figure 11.
The diaphragm fuel transfer pump which operates
directly
off
the
engine camshaft, draws fuel from
a
supply tank and delivers
it
through two filters to the
injection pump. The injection pump meters fuel
and
delivers
it, at
high pressure to the injection nozzle
at
the correct time
for
ignition.
The injection nozzle opens
at
a.
set
fuel pressure,
delivering fuel
in
a fine spray,
to
the precombustion
chamber
for
ignition.
The
nozzle remains open,
delivering fuel
as
long as,the fuel pressure remains
above the critical point.
Extra
fuel
is bled off after
each
injection cycle by
a
fuel
return line from the nozzle. An adapter combines the
return fuel with
the
flow-through fuel from
the
injection pump.
A
return line connected.atthis point,
returns
the
combined fuel back
to
the
fuel supply
tank.
CAUTION^
D,rt ln ,he
'
uel
8
y
8,em
l8 a
diesel engine's
worst enemy.
It
Is one of the major causes
of
diesel engine
failure.
Even
a
tiny
piece
of dirt
in
the Injection system
may stop your unit
When,
opening
any
part of. the fuel system
beyond the secondary fuel filter, place all parts In
a
pan
of
clean
diesel fuel
as
they
are
removed.
Before
installing new or
used
parts,
flush them thoroughly and Install while still wet.
MAINTENANCE
In addition
to
regular service periods, change
the
secondary fuel filter cartridge
if
the
engine shows
signs
of
starving from lack
of
fuel..
Remove
the
secondary filter
by
removing
the
large cap screw
in
the center of the filter cover. Use
care
when
replacing
the filter cartridge
to
avoid getting dirt into
the
injection pump passages.
When replacing
or
cleaning filters, bleed
the
fuel
system.
Do
this
by
opening
the air
bleed screw
located
on
top
of
the
secondary filter removal
cap
screw. Operate the hand priming lever
on
thetransfer
pump until no
air
bubbles flow from the bleed screw
hole,
then tighten the
bleed
screw. Return the priming
lever
to its
original position. See Figure
12.
If the transfer pump cam lobe
is
on
the high
side,
the priming lever
will
not
operate the pump. Tum the engine one revolution before
operating the priming lever.
AIR
CLEANER
MANIFOLD
HEATER
6LOW PLUS
CRANKCASE
BREATHER TUBE
FUEL
RETURN LINE
FUEL FILTER
SEDIMENT
BOWL
PRIMARY
FUEL FILTER
INJECTION
NOZZLE
INJECTION-
PUMP
'
SECONDARY
FUEL FILTER
WORK
TRANSFE
R
PUMP
PRIMING
LEVER
To
FILU
FILTER
NOTE: IF
PRIMING
LEVER
DOES
NOT
ENGAGE CRANK
ENGINE
ONE
REVOLUTION.
REMOVE
BLEED PLUG
FROM
TOP
OF
FUEL
FILTER
ALLOW
FUEL
TO FLOW
FROM
BLEEDER
HOLE
UNTIL
NO
A::R BUBBLES
APPEAR.
FIGURE 11. DIESEL FUEL SYSTEM (BEGINNING
WITH SPEC
S)
FIGURE
12.
BLEEDING FUEL SYSTEM
(PRIOR TO SPECS)
16
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