Fuel Pump And Vapor Discharge Valve - Lincoln Continental 1964 Shop Manual

(231}
10-27_,
PART
10-4
FUEL PUMP AND VAPOR DISCHARGE VALVE
Section Page
Section Page
1 Description and Operation .......... 10-27
3 Major Repair Operations ................. 10-29
2 Removal and Installation . . . . . . . ......... 10-28
D
DESCRIPTION AND OPERATION
DESCRIPTION
The fuel pump (Fig.
1)
is mount-
ed on the upper-portion of the cyl-
inder front cover.
A vapor discharge valve and re-
turn line adapter assembly (Fig.
1)
are contained within the fuel re-
turn port of the pump body. The
in-line replaceable fuel filter is con-
nected directly to the fuel outlet port
in the pulsator cover.
A heat shield (Fig. 1) is mounted
on the pump body and is retained
by three studs, nuts and washers.
OPERATION
FUEL PUMP
The fuel pump (Fig. 2) is me-
chanically actuated by the fuel
pump rocker arm, a push rod and
an eccentric sleeve mounted on the
front of the camshaft.
HEAT SHIELD
The flexible fuel pump diaphragm
is operated by a combination of
rocker arm action and calibrated
diaphragm spring tension.
FIG.
1-Fuel Pump and Vapor Discharge Valve
On the fuel intake stroke, the
camshaft eccentric raises the rocker
~rm
push rod and causes the rocker
arm to pull the. fuel pump diaphragm
against the diaphragm spring pres-
sure. This action draws fuel through
the intake valve into the pump
chamber and closes the outlet valve.
At the same time, fuel is drawn
from the fuel tank through the fuel
intake line to replace the fuel drawn
into the chamber.
As the camshaft eccentric con-
tinues to rotate, the rocker arm
relieves the pressure on the dia-
phragm spring and allows the spring
to move the diaphragm toward the
inlet and outlet valves, against the
pressure of the fuel built up in the
fuel inlet chamber. This action
causes the pump inlet valve to
close and opens the outlet valve. The
fuel is then forced through the pump
outlet to the fuel filter and car-
buretor. Fuel is delivered to the
carburetor only when the fuel
inlet valve in the carburetor is
open. The carburetor inlet valve
is closed by pressure of fuel on the
float when the specified fuel level
in the carburetor float chamber
is reached.
The fuel pump rocker arm serves
only to pull the diaphragm against
the diaphragm spring pressure dur-
ing the fuel inlet stroke. When there
is no demand for fuel from the
carburetor, the diaphragm spring
tension is not strong enough to force
the diaphragm upward against the
fuel pressure built up in the inlet
chamber of the pump. Thus, the up
and down rocker arm action con-
tinues, but the diaphragm remains
stationary until pressure against the
carburetor float is relieved by a de-
mand for fuel at the carburetor.
The pulsator diaphragm in the
fuel pump dampens the effect of fuel
pump pulsations on the carburetor
fuel inlet needle.
A relief vent is located in the
main body below the diaphragm.
The vent prevents air pressure build
up below the diaphragm.
VAPOR DISCHARGE VALVE
Hot vapors, which may form in
the pump due to atmospheric and
engine operating conditions, are re-
leased from the fuel pump and re-
turned to the fuel tank by means
of the vapor discharge valve and
adapter (Fig.
2)
and a fuel return
line.
When the hot vapors reach a pre-
determined temperature within the
pump, the calibrated thermostatic
spring gradually expands and moves
the valve plunger stem off of the
orifice in the valve seat insert. This
allows a metered flow of fuel and
vapors through the orifice, adapter,
and return line into the tank.
As fuel and vapors within the