Yamaha F30A Service Manual page 271

Symptom 2
Low compression
pressure
Throttle valve does
not fully open
—
Symptom 1: High engine idle speed
Symptom 2
Engine speed does
not decrease when
throttle control lever
is in fully closed
position
Throttle control
lever does not
return to fully closed
position
67C3K11
Cause 1
Valve clearance not
adjusted correctly
Damaged cylinder
head gasket
Damaged valve
Scratched piston or
cylinder
Damaged or worn
piston ring
Throttle control sys- Throttle cable not
tem malfunction adjusted correctly
Throttle link rod not
adjusted correctly
Air leakage into Damaged gaskets,
intake manifold spacer, and intake
(carburetor to cylin- manifold (carbure-
der head) tor to cylinder head)
Cause 1
Carburetor malfunc- Carburetors not
tion synchronized
Throttle stop screw
not adjusted cor-
rectly
Pilot screw not
adjusted correctly
Malfunction of the
carburetor internal
parts
Throttle control sys- Throttle cable not
tem malfunction adjusted correctly
Throttle link rod not
adjusted correctly
Throttle cam not
installed correctly
Troubleshooting the outboard motor
Cause 2 Checking step
Adjust the valve
—
clearance.
Disassemble and
check the cylinder
head and power
unit.
—
Check and adjust
the throttle cable.
Check and adjust
the throttle link rod.
Check the gaskets,
spacer, and intake
manifold (carbure-
tor to cylinder
head).
Cause 2 Checking step
Synchronize the
carburetors.
Adjust the throttle
stop screw.
Adjust the pilot
screw.
Disassemble and
check the carbure-
tor.
Check and adjust
the throttle cable.
Check and adjust
the throttle link rod.
Check the throttle
cam.
Refer
to
page
1
5-2
5-29
5-42
2
3
3-8
3-8
4
4-12
5
Refer
to
6
page
4-17
3-11
7
4-15
4-12
8
3-8
3-8
9
5-18
9-6