Do
not use galvanized lines, fittings, or fuel
tanks in underground portions of the fuel
system. Hazardous fuel leaks may be caused by electrolytic
corrosion from moisture and chemicals in the
soil
(galvanism).
Some safety ordinances prohibit the use of galvanized materials in
fuel systems and the use of threaded cast iron fittings as well.
The fuel system, located on the service side of the
engine, uses a transfer pump to deliver fuel from the
tank to a high pressure injection pump at about
12
to
14
psi (83-97 kPa). The injection lines deliver fuel to
the injectors at high pressure and act as fuel dis-
tributors to the injectors. The time interval between
individual injectors is varied in the pump by engine
speed. From the injection pump, metered fuel is
forced through a delivery valve to the injector lines at
about 1900 psi (13,110 kPa). When the cylinder air
reaches about 1000°F (538°C) on the compression
stroke, the injector sprays fuel into the hot com-
pressed air where
it
ignites. The delivery valve in the
injection pump and a pintle valve in the injector
assists the precision timed injection of fuel into the
cylinder.
.
Excess fuel is returned to the tank after each injection
cycle by a fuel return line from the nozzle. An adapter
combines the leak-off fuel with the flow-through fuel
from the injection pump. A return line connected at
this point returns the combined fuel back to the fuel
supply tank.
A diesel engine cannot tolerate dirt in the fuel
svstem. It is one of the maior causes of diesel
engine failure. 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.
FILTER SYSTEM
The sediment bowl has a fine mesh screen which
blocks dirt and water entry into the transfer pump,
Figure 10. The dirt and water remain in the sediment
bowl which should be removed for cleaning as
required. The primary and secondary fuel filters are
replaceable spin-on units that clean the fuel of
extremely fine particles before it goes to the injection
pump.
These filters are mounted
on
a common casting
which bolts to the oil fill tube. Positive filtration is
assured because the engine won’t run when either
filter is loose
or
missing.
Average pore size of the second filter is
.0005
(0.0127 mm) smaller than the first filter. This means
most particles escaping the first filter are trapped in
the second filter.
Water
in
Fuel
Filters: Drain water periodically as
required from both filters. Replace primary filter every
600
hours and secondary filter every
3000
hours.
When replacing filter, tighten screw until gaskets
touch base, then tighten screw
1
to 1-1/2 turns.
FUEL TANK AND
LINES
Where a separate fuel tank
is
used, install
so
the
vertical distance from bottom of the tank to the fuel
pump does not exceed six feet. Auxiliary fuel pumps
are available to provide an additional eight-foot lift.
Avoid gravity feed of fuel to the engine. Provide a
siphon break if tank is above pump. When sharing a
fuel tank, do not connect to an existing line at a point
above the fuel supply level.
These diesel engines require a fuel supply line and a
separate return line. Install the fuel supply line from
tank to the 1/8-inch pipe inlet in the fuel pump.
Connect fuel return line to fitting at injection pump.
See Figure
10.
Use approved flexible fuel lines at the
engine to absorb vibration. Be sure there are no air
leaks in the suction line.
Install a shut-off valve in the tank for service con-
venience.
FUEL TRANSFER PUMP
The fuel transfer pump (Figure ll),
is
a diaphragm
and check valve type pump operated
by
a cam lobe on
the engine camshaft. The pump cam follower has a
wide surface to prevent wear as it rides on the
camshaft lobe. The priming lever is manually
operated to prime and bleed the system.
The diaphrgam spring maintains required fuel
pressure to the injection pump. Fuel pressure should
be 12-14 psi (83-97 kPa) when operating at 1800 rpm.
ROCKER
ARM
SPRING
...
COVER
DIAPHRAGM
ASSEMBLY
DIAPHRAGM
SPRING
ROCKER ARM
LINK
FIGURE
11.
FUEL TRANSFER
PUMP
17
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