Outboard motor troubleshooting
Symptom 1: Unstable engine idle speed, poor acceleration, poor performance, limited engine
speed, or en
gine stalls.
Symptom 1: High engine idle speed.
Symptom 1: Engine overheats.
Compression pressure
is low
Compression leakage Measure the compression pressure.
Check the valve for bends or stuck.
Check the decompressor for proper
operation.
Check the piston and piston ring for
damage.
Check the cylinder for damage.
Improper valve timing Check the valve timing.
Symptom 2 Cause Checking step
Fuel not supplied — Check that the air vent screw is open.
Throttle valve does not
move properly
Carburetor malfunction Check the throttle valve for proper move-
ment.
Throttle link and throttle cable
not installed properly
Adjust the throttle link and throttle cable.
Spark is weak — Check the CDI unit air gap.
Improper fuel and air
amount supplied
Choke valve does not operate
properly
Check the choke valve operation.
Carburetor malfunction Adjust the pilot screw.
Disassemble and clean the carburetor.
Air leakage (carburetor to cylin-
der head)
Check the O-ring and gaskets of the car-
buretor and intake manifold.
Symptom 2 Cause Checking step
Improper fuel and air
amount supplied
Carburetor malfunction Adjust the pilot screw.
Disassemble and clean the carburetor.
Throttle link and throttle cable
not installed properly
Adjust the throttle link and throttle cable.
Symptom 2 Cause Checking step
Cooling water not dis-
charged from the cooling
water pilot hole
Clogged cooling water inlet Check the cooling water inlet.
Water pump impeller malfunc-
tion
Check the impeller.
Check the pin.
Water leakage from the water
pump housing
Check the insert cartridge.
Check the outer plate cartridge.
Check the water pump housing.
Leak or clogged cooling water
passage
Check the water pipe for damage and
proper installation.
Check the cooling water passage.
— Thermostat malfunction Check the thermostat.
Symptom 2 Cause Checking step
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