Section XI. FULL SYSTEM
and returned to fuel tank. Filtered fuel flows up center
3-67. General
of filter housing into a passage through cover then down
a. Fuel System for Engine Model 687C-18-ES. The
rear of housing to fuel manifold, which distributes fuel to
fuel supply system for this engine consists of a fuel tank,
the injection pumps. A cam activated injection pump for
shutoff valve, primary filter, priming pump, secondary
each cylinder, forces fuel through an injection line to
filter, and a transfer pump that is built into the fuel
proper fuel injector where a definite quantity of fuel is
injection pump. It also includes a return flow line from
forced into precombustion chamber at the proper time.
injectors to pump, and return lines through shutoff valve
d. Fuel System Flushing Procedure for Engine Model
to fuel tank. The injection pump forces a metered
D333TA.
amount of fuel through lines to injectors, and into engine
(1)Open vent valve at front of filter cover.
cylinders at high pressure. An overspeed governor
(2)Operate primer pump (para 2-8ar) several times,
driven by tachometer drive, activates shutdown lever on
until a solid stream of fuel flows out of the drain tube,
injection pump through a microswitch controlled circuit,
indicating that all air has been flushed from the system.
when rpm exceeds 1935 + or - 15 rpm.
(3)Close the vent valve.
b. Fuel System Flushing Procedure for Engine Model
Note: The fuel system may also be flushed by
687C-18-ES.
using transfer pump to force fuel out of drain tube.
(1)Disconnect fuel line at pump inlet and place end
of line in a suitable container.
Open vent valve and operate starter for
(2)Pump the hand primer (para 2-8ar) several times
approximately thirty seconds, or until a solid stream
to flush the lines and filters.
of fuel flows out of drain tube, whichever requires
(3)Reconnect fuel line to pump inlet. Be sure the
the shorter time, then close vent valve.
fuel line connector screws are set at proper torque of
420 inch-pounds.
3-68. Fuel Injector and Fuel Line
Note: New fuel line connector washers should
a. General. A fuel injector or fuel line that is loose,
be installed every time the fuel line connector
damaged, or defective will effect diesel engine
screws are loosened.
operation. When it is suspected that a fuel injector is
(4)Disconnect injector lines at the injectors.
defective, the defective injector can be isolated by the
(5)Crank the engine with starter for thirty seconds.
following process of elimination: (1) Loosen fuel line
(6)Reconnect injector lines.
coupling nut at fuel injector while engine is idling, and
observe engine performance.
Note: A characteristic of the Roosa-Master fuel
(2)If idling speed slows down, the injector is working.
injection pump is that if engine misfiring occurs and it is
(3)If there is no noticeable difference in engine
traced to a certain cylinder in which no combustion is
speed, that injector is defective. Repeat on remaining
taking place, the cause may be a nozzle valve sticking
five injectors. Replace defective or damaged fuel line,
open in the cylinder which immediately preceds that
or injector.
cylinder in the firing order. During injection to the
cylinder which has the nozzle valve sticking in the open
b. Removal and Installation.
position, the fuel rushes into that cylinder with no
(1)On engine model 687C-18-ES.
restriction, causing a scavenging effect in the pump
(a)Refer to figure 3-51 and remove items in
distributor rotor and a void which cannot be reached to a
numerical sequence.
sufficient degree to provide opening pressure of fuel to
(b)Install by reversing procedure above.
the following nozzle valve. Hence, no combustion can
(2)On engine model D383TA.
take place.
(a)Refer to figure 3-52 and remove glow plug to
prevent damage.
c. Fuel System for Engine Model D333TA. The fuel
(b)Remove remaining items in numerical sequence.
is drawn from supply tank by a gear type transfer pump
(c)Install by reversing procedure above.
that forces fuel through a drilled passage in filter
housing to the outside of filter element. A spring loaded
3-69. Air Cleaners
by-pass valve on front of filter housing maintains a
a. Used by Engine Model 687C-18-ES on Crane
maximum pressure of approximately 15 psi on the fuel
Model 855BG2.
in filter housing; as indicated on fuel pressure gage
(1)Removal and installation. Refer to figure 3-53,
mounted on housing. This fuel transfer pump supplies
remove items 1 through 5 in numerical sequence, and
more fuel than is required by engine, or to maintain 15
psi pressure. Excess fuel is by-passed around valve
3-62
