Evinrude 4906B 4HP 1969, Owner'S Manual

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Next, drill the appropriate size hole for a
suitable fitting to pickup the cylinder vacu-
um. Install the cover plate with the
fi
tting
in place. Mount the fuel pump in a conven-
ient location, and then connect the vacuum
hose. Plug the hole in the intake manifold
just below the carburetor. Purchase a regu-
lar fuel tank. Because the new system will
only have one hose, a new quick-disconnect
fi tting must also be purchased and and con-
nected to the engine.
TROUBLESHOOTING
Observe the stamped markings on the
pressure-type fuel tank adjacent to each
fi tting; one for air and the other for fuel.
Also, observe the rib on one hose running
the full length from the tank to the engine.
This rib will help to identify
the same hose
at the tank and the engine.
With the fuel tank fill cap securely clos-
ed, insert a screwdriver into the fuel line
quick-disconnect at the engine to hold the
check valve open. Now, work the primer
pump on the fuel tank and fuel should squirt
out the quick-disconnect because the screw-
dr iver is holding the check valve open.
If fuel is not present at the fitting, the
pressure fuel tank primer pump or the check
valve in the fuel pickup at the bottom of the
fuel tank may be defective.
If the engine runs for short periods and
then shuts down from lack of fuel, the
problem may be lack of air pressure in the
tank. To check for air pressure, after the
engine has run for just a short period, open
the fill cap very slightly. A hissing sound
Pressure-type fuel tank with the fuel line (left), and
air line (right), connected. Notice the rib on the fuel
hose which extends the full length to the engine.
TROUBLESHOOTING 4-9
Back side
of
the double fuel/air connector. In this
photograph, the air line is on the left and the fuel on
the right.
indicating escaping air should be heard.
Lack of air may be caused by defective 0-
rings at the connectors, or because the
check valve in the intake manifold is not
properly seated.
Integral Fuel Tank System
On small engines equipped with an inte-
gral fuel tank above the flywheel, or else-
where on the engine, the filter in the tank
may be plugged. To check the fuel flow,
disconnect the fuel line at the carburetor
and fuel should flow from the line if the
shut-off valve is open. If fuel is not pres-
ent, the usual cause is a plugged filter in the
fuel tank. It is very difficult to determine
if a porcelain-type fil ter is plugged. The
general appearance that the filter is satis-
factory may be a false indication. There-
fore, if the filter is suspected, the best
Pressure-type fuel tank with the air and fuel lines
attached through
a
double connector. The fill cap must
be tightly closed for the system
to
operate properly.