Evinrude 4906B 4HP 1969, Owner'S Manual

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fuel pump, or by a leak in the line from the
fuel tank to the fuel pump.
Aged fuel left
in the carburetor and the formation of var-
nish could cause the needle to stick in its
seat and prevent fuel flow into the bowl. A
defective choke may also cause problems.
WOULD YOU BELIEVE, a majority of start-
ing troubles, which are traced to the fuel
system, are the result of an empty fuel tank
or aged fuel.
Fuel will begin to sour in three to four
months and will cause engine starting prob-
lems. Therefore, leaving the motor setting
idle with fuel in the carburetor, lines, or
tank during the off-season, usually results in
very serious problems. A fuel additive such
as Sta-Bil may be used to prevent gum from
forming during storage or prolonged idle
periods.
For many years there has been the wide-
spread belief that simply shutting off the
fuel at the tank and then running the engine
until it stops is the proper
procedure before
storing the engine for any length of time.
Right? WRONG.
First, it is NOT possible to remove all
fuel in the carburetor by operating the en-
gine until it stops. Considerable fuel is
Female fuel line connector ready
to
be mated with
the male portion of the connector.
TROUBLESHOOTING 4-5
trapped in the float chamber and other
passages and in the line leading to the
carburetor. The
ONLY
guaranteed method
of removing ALL fuel is to take the time to
remove the carburetor, and drain the fuel.
Secondly,
if the engine is operated with
the fuel supply shut off until it stops the
fuel and oil mixture inside the engine is
removed, leaving bearings, pistons, rings,
and other parts without any protective lu-
bricant.
Propel" procedure involves: Shutting off
the fuel supply at the tank; disconnecting
the fuel line at the tank; operating the
engine until it begins to run ROUGH; then
stopping the engine, which will leave some
fuel/oil mixture inside; and finally removing
and draining the carburetor. By disconnect-
ing the fuel supply, all SMALL passages are
cleared of fuel even though some fuel is left
in the carburetor. A light oil should be put
in combustion chamber as instructed in the
Owners Manual. On some model carbure-
tors, the high-speed orifice plug can be
removed to drain the fuel from the carbure-
tor.
Choke Problems
When the engine is hot, the fuel system
can cause starting problems. After a hot
engine is shut down, the temperature inside
the fuel bowl may rise to 200
0
F and cause
the fuel to actually boil. All carburetors
are vented to allow this pressure to escape
to the atmosphere. However, some of the
fuel may percolate over the high-speed noz-
zle.
Fouled spark plug, possibly caused by operator's
habit of over-choking or a malfunction holding the
choke closed. Either
of
these conditions delivered
a
too-rich fuel mixture
to
the cylinder.