105
FUEL SYSTEM
COMPONENTS
6
COMPONENTS
The carbureted fuel system consists of the follow-
ing components:
• Fuel pump
• Carburetor
• Intake manifold assembly
Fuel Pump
The fuel pump is a diaphragm-displacement type
and is operated by changes in crankcase pres-
sure. A pulse hose connects the pump to the cyl-
inder/crankcase. Alternately, vacuum and
pressure in the crankcase are transmitted to the
pump diaphragm.
Carburetor
The carburetor meters and distributes the fuel to
the engine. It controls engine speed and power
output by varying the intake charge density. To
react correctly to a wide range of operating condi-
tions, the carburetor has multiple fuel mixing cir-
cuits.
Fuel mixture enrichment for cold starting is con-
trolled by a choke.
IMPORTANT: The 9.9/15 models use a tamper
resistant carburetor. Changing original factory fuel
mixture calibrations beyond the limits allowed by
the tamper resistant device is a violation of federal
law. Any carburetor adjustments beyond preset
limits become the responsibilty of the servicing
technician and/or the owner. Refer to Emissions
Compliance on p. 107.
Intake Manifold
The intake manifold provides the mounting sur-
faces to adapt the carburetor to the cylin-
der/crankcase assembly. It contains the leaf
valves which control the intake charge to each cyl-
inder.
26417
9.9/15 Model
1. Choke
32958
TYPICAL
1. Intake manifold
COA1524
1
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