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3-18
FUEL AND VACUUM PUMP
ENGINE FUEL AND EXHAUST SYSTEMS
(9 2)
SECTION 3-D
FUEL AND VACUUM PUMP
CONTENTS OF SECTION 3-D
Paragraph
Subject
Page
3-16
Description and Operation of Fuel
and Vacuum Pump
.
. .
3-18
3-17
Fuel Pump Inspection and Test
. .
.
3-19
Paragraph
Sublect
Page
3-18
Vacuum Pump Inspection and Test
3-20
3-19
Fuel and Vacuum Pump
Repairs.
3-21
SERVICE BULLETIN REFERENCE
Bulletin
No.
Page No.
SUBJECT
3-16 DESCRIPTION AND OPERATION
OF FUEL AND VACUUM PUMP
a. Description of Pump
The AC type AJ combination fuel and
vacuum pump is used on all series engines.
The pump assembly for Series 70 differs from
the pump for Series 40-50 only in the shape of
rocker arm and in the use of an air dome on
the fuel outlet of the Series 70
pump.
The pump assembly, which is mounted on
right side of engine crankcase at the front, is
operated by an eccentric on the engine cam-
shaft which actuates the pump rocker
arm.
The single rocker arm actuates both the fuel
and the vacuum sections of the pump through
separate links
which
permit each
section
to
function independently of the other
section.
See figure 3-25.
The fuel and vacuum sections form two sep-
arate,
independently
operating
diaphragm type
pumps.
They are combined in one assembly for
compactness and to permit operation from one
eccentric on the engine camshaft .
A fuel filter,
consisting
of a metal bowl and
a fine mesh screen, is incorporated in the fuel
A-OUTLET VALVE
B-COVER PLATE
C-VACUUM
DIAPHRAGM
SPRING
D-VACUUM
DIAPHRAGM
E-FUEL LINK
F-ROCKER
ARM PIN
G-ROCKER ARM
H-ROCKER ARM SPRING
I-FUEL DIAPHRAGM
J-FUEL
CHAMBER
K- FILT ER
SCREEN
--+--J
l-BOWL
• • • •
m
M-OUTLET VALVE
N-FUEL DIAPHRAG
M
SPRING
r:=-----K
O-VACUUM LINK
-----L
P-AIR DOME
Q-AIR CHAMBER
R-GASKETS
..-----8
=-:i--C
R--tiiii:::~=
OUT"'mii~.
Q
Figure
3-25-Combination
Fuel and Vacuum Pump-Sectional View
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