TM 5-4320-218-15
c. Cylinder firing order. Because of the V-
unit from the trailer. The unit is lifted by
type construction of the engine the interval of
means of the lifting eye located in the center
crankshaft rotation between firing of the cylin-
of the unit.
der is as follows: 180 degrees between cylin-
ders No. 1 and No. 3, 270 degrees between cyl-
79. Engine Cleaning and Inspection
inders No. 3 and No. 4, 180 degrees between
After Reassembly
cylinders No. 4 and No. 2, and 90 degrees be-
a. Before reinstalling the engine, be sure
tween cylinders No. 2 and No. 1
that the cleaning, inspection, and repair proce-
dures for each component have been performed,
78. Engine and Pump Removal for
following instructions contained in succeeding
Disassembly
sections of this chapter.
Whenever it becomes necessary to remove the
b. Remove all dirt, grease, grit, and other
engine and pump assembly from its mounting
foreign matter from the mounting surfaces.
on the trailer for overhaul purposes, the engine
and pump assembly is removed as a unit. The
c. Clean all the mounting screws, lockwash-
pump is directly connected to the engine. The
ers, and nuts with a stiff wire brush and an
crankshaft extends into the pump and serves
approved cleaning solvent. Inspect each thread-
as an impeller shaft for the pump, Before the
ed surface for corrosion and damage.
pump and engine can be removed certain com-
d. Replace all mounting screws and nuts
ponents of the pump must be removed as fol-
which are corroded or otherwise damaged.
lows :
a. Remove the pump suction manifold.
80. Engine and Pump Installation After
b. Remove the pump discharge manifold.
Reassembly
c. Disconnect the fuel line from the engine
fuel pump to the fuel tank.
The engine-pump assembly can either be in-
d. Disconnect the suction gage at the suction
stalled as a unit, or each assembly can be in-
manifold.
stalled separately. Position each component
e. Remove the nuts, bolts, and lockwashers
and secure it with the attaching parts, revers-
securing the pump and engine to the trailer
ing the procedure described in paragraph 78.
frame.
Tighten each attached part and rotate the pump
f. Use a lifting device such as a crane and
by hand cranking the engine to see that it turns
lift off the engine and pump as an integral
freely.
Section III. FUEL PUMP
the outlet valve opens, allowing fuel to flow
81. Description
through the outlet to the carburetor. The pump
The diaphragm-type fuel pump is mechani-
has an integral filter and pulsator. The pulsa-
cally operated off a cam on the engine camshaft
tor is designed to minimize the flow variations
through the fuel-pump adapter. The cam action
experienced with a two-cycle pump stroke, and
is transmitted to the pump rocket arm which,
to provide increased flow characteristics up to
i n turn, pulls down the pump diaphragm
50 percent. Figure 9 shows the fuel pump and
against the pressure of the diaphragm spring,
the adapter mounted on the engine. An ex-
producing a vacuum `in the fuel chamber. Pres-
ploded view of the fuel pump and adapter is
sure in the outlet line forces the outlet valve
shown in figure 24.
to close against the vacuum and pulls the inlet
valve open, Atmospheric pressure in the sup-
ply tank forces fuel through the inlet into the
82. Fuel Pump Disassembly (fig. 24)
pump fuel chamber. On the return stroke of
the rocket arm, the diaphragm spring forces the
a. Remove the fuel pump and the fuel-pump
diaphragm upward, the inlet valve closes, and
adapter from the engine.
