5.9
Section 5
Fuel System and Governor
5
Figure 5-10. Installing Float and Fuel Inlet Needle.
4. Install the bowl gasket, fuel bowl, bowl retaining
screw gasket, and bowl retaining screw or fuel
solenoid.
Torque the bowl retaining screw to 5.1-6.2 N·m
(45-55 in. lb.).
Fuel Shut-off Solenoid
Many engines are equipped with a fuel shut-off
solenoid installed in place of the bowl retaining screw
to eliminate backfiring when the engine is shut down. If
backfiring occurs on engines equipped with this
solenoid, verify that the correct shutdown procedure is
being used. In order for the solenoid to be effective,
the engine must be running between half and full
throttle when the key is turned off. Next, check the
battery to ensure that it is not discharged or faulty. A
minimum of 7.3 volts DC is required to activate the
solenoid. Also check to see that the ground lead from
the carburetor body to the air cleaner base mounting
screw is properly connected.
If these check out, the solenoid should be removed for
bench testing. Remember to shut off the fuel supply
and catch any fuel spilling from the carburetor as the
solenoid is removed.
Bench test the solenoid by grounding the solenoid
case and applying 12 volt DC to the spade terminal. If
the plunger does not retract, the solenoid is faulty and
must be replaced. Always use a new fuel bowl gasket
whenever the solenoid is installed. Refer to the wiring
diagram in Section 7 and connect the fuel shut-off
solenoid.
Figure 5-11. Fuel Shut-Off Solenoid.
High Altitude Operation
When operating the engine at altitudes of 1830 m
(6000 ft.) and above, the main fuel mixture tends to get
over rich. An over-rich mixture can cause conditions
such as black, sooty exhaust smoke, misfiring, loss of
speed and power, poor fuel economy, and poor or slow
governor response.
To compensate for the effects of high altitude, a
special high altitude main jet can be installed. High
altitude jets are sold in kits which include the jet and
necessary gaskets. Refer to the Parts Manual for the
engine being serviced for the correct kit number.
Unitized Throttle and Choke Control
Some engines are equipped with a ‘‘unitized’’ throttle
and choke control. This assembly controls the choke
and engine speed with a single lever. See Figure 5-12.
Throttle Cable Adjustment
1. Loosen the throttle control cable clamp. See
Figure 5-12.
Figure 5-12. Speed Control Bracket with Unitized
Throttle/Choke Control.
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