Yamaha F40B - Page 271

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