Fuel - Yamaha 55DEHD Service Manual

Symptom 1: Unstable engine idle speed, poor acceleration
Symptom 2
Throttle stop screw
adjusting improperly
Pilot screw adjusting
improperly
—
Throttle cable adjusting
improperly
Throttle link length
improperly
Fuel supplied to the
carburetor improperly
Fuel not sup-
plied properly
Carburetor malfunction
Deterioration or dirty
—

fuel

6885J11
Cause 1 Cause 2
Kinked fuel
hose
Fuel joint
malfunction
Fuel filter
element
malfunction
Fuel pump
malfunction
Pilot screw set-
tings improperly
Throttle valve
stuck or
damage
Jet or nozzle
clogged and or
float damaged
Float height
improperly
Trouble shooting the power unit
Checking step
Check and adjust the
—
throttle stop screw.
Check and adjust the
—
pilot screw.
Check and adjust the
—
throttle cable.
Check and adjust the
—
throttle link length.
Check the fuel hose
kinked. Repair the fuel
hose.
Check the fuel joint
pressure.
Check the fuel filter for
clog.
Check the fuel pump.
Check and adjust the
pilot screw settings.
Disassemble and
check the carburetor.
— Replace new fuel
Refer
to
1
page
3-8
4-14
2
3-7
3-6
3
3-2
4-6
4
3-3
5
4-7
4-15
6
—
4-13 7
—
8
9
9-4