Advertisement
W E 1 SYSTEM-FUEL
PUMP
14-75
PART 9
FUEL PUMP AND TANK
FUEL PUMP
Description
Three different models of fuel pumps are used in
production. The same basic design applies to all three
models. The service procedures for testing are the
same.
Fuel pump model MS-3674S, shown in (Fig. l), is
used exclusively on the 170/225 cubic inch 6 cylin-
der engine. Model MS-3673S, shown in (Fig. 2) is used
on the 273-318 cubic inch V-8 engine. Model MS-
3672S, shown in (Fig. 3), is used on the 361-383-426
cubic inch engine.
The fuel pumps are driven by an eccentric cam that
is cast on the camshaft in the 170/225 and 361-383-
H
V N
ICa
64x413
Fig. 1-Fuel
Pump Assembly
I1
70-225 Cu. In. EngineJ
m
64x 41 4
Fig. 2-Fuel
Pump Assembly 1273-31 8 Cu. In.
Engine)
426 cubic inch engines, or by a pressed steel eccentric
cam mounted on the gear end of the camshaft in the
273-318 cubic inch engine.
As the camshaft rotates, the eccentric cam presses
down on the pump rocker arm. (On the 361-383-426
cubic inch engine, a push rod operates between the
camshaft and the fuel pump rocker arm.) This action
lifts the pull rod and diaphragm upwards against the
fuel pump main spring, thus creating a vacuum in the
valve housing and opens the inlet valve and fuel is
drawn into the valve housing chamber. On the return
stroke the main spring forces the diaphragm to the
down
position, which closes the inlet valve and expels
the fuel in the valve housing chamber through the
outlet valve, to the fuel filter and the carburetor.
The fuel pump is of the pressed steel type and can-
not be disassembled for service. If a pump malfunc-
tion occurs, remove the old pump and install a new
one.
The fuel filters (ceramic or paper) should be
changed every 20,000 miles, to insure having an un-
restricted flow of fuel at all times.
Do not attempt to
clean.
TESTING FUEL PUMPS (On
the Engine)
If the fuel pump fails to supply fuel properly to the
carburetor, the following tests should be made before
removing the fuel pump from the vehicle.
If leakage is not apparent, test the pump for pres-
sure.
64 x 415
Fig. 3-Fuel
Pump Assembly 1361,383 and 4 2 6
Cu.
In.
Eng.J
Hide quick links:
Advertisement
