Evinrude 4906B 4HP 1969 Owner's Manual page 95

4-4 FUEL
When this choke valve is closed, a very
rich fuel mixture is drawn into the engine.
The throat of the carburetor
referred to as the "barrel."
installed on engines covered in this manual
all have a single metering jet with a single
throttle and choke
carbu retors are fed by one float and cham-
ber.
4- 3 FUEL SYSTEM
The fuel system includes the fuel tank,
fuel pump, fuel filters, carburetor,
ing lines, with a squeeze
associated parts to connect it all together.
Regular maintenance
obtain maximum performance,
changing the fuel filter at regular intervals
and using FRESH fuel.
price of fuel, removing
been standing unused over a long period of
time is still the easiest and least expensive
preventive maintenance
In most cases this old gas, even with
some oil mixed with
harmful effects in an automobile using regu-
lar gasoline.
If a sudden increase in gas consumption
is noticed, or if the engine does not perform
Commercial additives,
to
keep the fuel in the tank fresh.
conditions, such additives. will
up to
"souring" for twelve months.
is usually
Carburetors
plate. Single barrel
connect-
bulb, and the
of the fuel system to
is limited
Even with the high
gasoline that has
possible.
it,
can be used without
such as Sta-bii, may be used
Under favorable
prevent the fuel from
Damaged piston, possibly caused by insufficient
to
mixed with the fuel; using too-low
using fuel that had "soured" (stood too long without
preservative additive).
properly, a carburetor
boil-out, or
may be required.
4-4 TROUBLESHOOTING
The following paragraphs
derly sequence of tests to pinpoint problems
in the system.
used for some time and fuel has remained in
the carburetor,
may have formed.
be the cause of hard starting,
failure of the engine to operate.
Fuel Problems
Many times
caused by a plugged fuel filter, a defective
Fuel connector
rings have a relative
regular intervals,
an octane fuel;
overhaul,
replacement of the fuel pump
provide an or-
If an engine has not been
it is possible that varnish
Such a condition
or complete
fuel system troubles
with the O-ring visible.
short life and must be replaced at
as detailed in the text.
oil
or
a
including
could
are
These 0-