Reference
Tool
Stock No.
(Pars.)
223a
Expander, piston ring, 5% in. piston size...............................................
41-3160.800.057
223c
225b
Puller, cylinder sleeve ............................................................................
41-6272.300.500
222c
Grinder, crankshaft .................... ............................................................
40-5145.500.510
Section IIl. FUEL PUMP
180. Description
The fuel pump is mounted at the foot of the crankcase on the compressor side of the unit. The rotation of the
camshaft eccentric actuates the rocker arm which pulls the diaphragm downward against the diaphragm spring, creating a
vacuum within the pump chamber. On the suction stroke of the pump, fuel from the fuel tank enters through the inlet into
the sediment bowl, is filtered by the screen, and passes into the pump chamber through the inlet valve. On the return
stroke, the diaphragm spring pushes the diaphragm upward, forcing fuel from the pump chamber through the outlet valve
and to the carburetor. When the carburetor bowl is filled, the flute in the carburetor will shut off the needle valve, thus
creating a pressure within the pump chamber. This pressure will hold the diaphragm downward against the diaphragm
spring pressure, where it will remain inoperative in the downward position until the carburetor requires further fuel and the
carburetor needle valve opens. The rocker arm spring supplies the tension which keeps the rocker arm in constant
contact with the camshaft.
181. Fuel Pump Disassembly
a. Remove fuel pump (par. 75a).
b. Before disassembling the fuel pump, file a mark across the diaphragm flanges. These file marks will serve as a
guide during reassembly to make certain that the inlet and outlet holes will match the position of the fuel line.
c. Loosen the thumb nut at the top of the lifting bail (1) and lift the bail, metal fuel bowl (2), bowl gasket (3), and
screen (4) from the pump.
d. Remove the ten cover screws (5) and lockwashers (6) and lift the pump cover (7) from the assembly. Invert the
pump cover, and remove the two retainer screws (11), the valve cage
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