Yamaha F15 Owners Manual

							 
Maintenance 
55 
2. Screw the garden hose connector onto a
garden hose which is connected to a
fresh water supply.
3. With the engine off, turn on the water tap
and let the water flush through the cool-
ing passages for about 15 minutes. Turn
off the water and disconnect the garden
hose.
4. When flushing is complete, reinstall the
garden hose connector on the fitting on
the bottom cowling. Tighten the connec-
tor securely.
CAUTION:
 
ECM00540  
Do not leave the garden hose connector
loose on the bottom cowling fitting or let
the hose hang free during normal opera-
tion. Water will leak out of the connectorinstead of cooling the engine, which can
cause serious overheating. Be sure the
connector is tightened securely on the fit- 
ting after flushing the engine.
NOTE:
 
 
When flushing the engine with the boat in
the water, tilting up the outboard motor un-
til it is completely out of the water will
achieve better results. 
 
For cooling system flushing instructions, 
see page 51. 
EMU28450 
Cleaning the outboard motor 
After use, wash the exterior of the outboard
motor with fresh water. Flush the cooling
system with fresh water.
NOTE:
 
For cooling system flushing instructions, see 
page 51. 
EMU28460 
Checking painted surface of motor 
Check the motor for scratches, nicks, or flak-
ing paint. Areas with damaged paint are
more likely to corrode. If necessary, clean
and paint the areas. A touch-up paint is avail-
able from your Yamaha dealer. 
1. Fitting
2. Garden hose connector
3. Garden hose
1
23
ZMU04887
ZMU02052 
						

							 
Maintenance 
56 
EMU28486 
Periodic maintenance
WARNING
 
EWM01070  
Be sure to turn off the engine when you
perform maintenance unless otherwise
specified. If you or the owner is not famil-
iar with machine servicing, this work
should be done by your Yamaha dealer or 
other qualified mechanic.
Maintenance, replacement, or repair of
the emission control devices and sys-
tems may be performed by any marine
engine repair establishment or individual.
All warranty repairs, however, including
those to the emission control system,
must be performed by an authorized
Yamaha marine dealership. 
A service manual is available for purchase
through your Yamaha dealer for owners who
have the mechanical skills, tools, and other
equipment necessary to perform mainte-
nance not covered by this owner’s manual. 
EMU28510 
Replacement parts 
If replacement parts are necessary, use only
genuine Yamaha parts or parts of the same
type and of equivalent strength and materi-
als. Any part of inferior quality may malfunc-
tion, and the resulting loss of control could
endanger the operator and passengers.
Yamaha genuine parts and accessories are
available from your Yamaha dealer. 
						

							 
Maintenance 
57 
EMU28522 
Maintenance chart 
Frequency of maintenance operations may be adjusted according to the operating condi-
tions, but the following table gives general guidelines. Refer to the sections in this chapter for
explanations of each owner-specific action.
NOTE:
 
When operating in salt water, turbid or muddy water, the engine should be flushed with clean 
water after each use.
The “” symbol indicates the check-ups which you may carry out yourself.
The “” symbol indicates work to be carried out by your Yamaha dealer. 
Item ActionsInitial Every
10 hours 
(1 month)50 hours 
(3 
months)100 
hours (6 
months)200 
hours (1 
year)  
Anode(s) (external)Inspection / replace-
ment
Anode(s) (internal)Inspection / replace-
ment
Battery Inspection / charging
Cooling water pas-
sagesCleaning
Cowling clamp Inspection
Fuel filter (can be dis-
assembled)Inspection / cleaning
Fuel system Inspection
Fuel tank (Yamaha por-
table tank)Inspection / cleaning
Gear oil Change
Greasing points Greasing
Idling speed (carbure-
tor models)Inspection
Power trim and tilt unit Inspection
Propeller and cotter pinInspection / replace-
ment
Shift link / shift cable Inspection / adjustment
ThermostatInspection / replace-
ment
Throttle link / throttle 
cable / throttle pick-up 
timingInspection / adjustment 
						

							 
Maintenance 
58 
EMU28874 
Maintenance chart (additional) 
EMU28910
NOTE:
 
When using lead or high-sulfur gasoline, inspecting valve clearance may be required more 
frequently than every 500 hours. 
Water pumpInspection / replace-
ment
Engine oil Inspection / change
Oil filter (cartridge) Change
Spark plug(s)Cleaning / adjustment / 
replacement
Timing beltInspection / replace-
ment
Valve clearance (OHC, 
OHV)Inspection / adjustment 
Item ActionsEvery
500 hours (2.5 years) 1000 hours (5 years) 
Timing belt Replacement
Exhaust guide, exhaust 
manifoldInspection / replace-
ment 
Item ActionsInitial Every
10 hours 
(1 month)50 hours 
(3 
months)100 
hours (6 
months)200 
hours (1 
year) 
						

							 
Maintenance 
59 
EMU28931 
Greasing 
Yamaha marine grease (Water resistant grease) 
F9.9ER, T9.9ER, F15PR
ZMU02330 
						

							 
Maintenance 
60 
F9.9MH, T9.9EH, F15MH, F15EH, F15PH
ZMU02331 
						

							 
Maintenance 
61 
EMU28952 
Cleaning and adjusting spark plug
WARNING
 
EWM00560  
When removing or installing a spark plug,
be careful not to damage the insulator. A
damaged insulator could allow external
sparks, which could lead to explosion or 
fire. 
The spark plug is an important engine com-
ponent and is easy to inspect. The condition
of the spark plug can indicate something
about the condition of the engine. For exam-
ple, if the center electrode porcelain is very
white, this could indicate an intake air leak or
carburetion problem in that cylinder. Do not
attempt to diagnose any problems yourself.
Instead, take the outboard motor to a
Yamaha dealer. You should periodically re-
move and inspect the spark plug because
heat and deposits will cause the spark plug
to slowly break down and erode. If electrode
erosion becomes excessive, or if carbon and
other deposits are excessive, you should re-
place the spark plug with another of the cor-
rect type.
Before fitting the spark plug, measure the
electrode gap with a wire thickness gauge;
adjust the gap to specification if necessary.When fitting the plug, always clean the gas-
ket surface and use a new gasket. Wipe off
any dirt from the threads and screw in the
spark plug to the correct torque.
NOTE:
 
If a torque-wrench is not available when you
are fitting a spark plug, a good estimate of
the correct torque is 1/4 to 1/2 a turn past fin-
ger-tight. Have the spark plug adjusted to the
correct torque as soon as possible with a 
torque-wrench. 
EMU28962 
Checking fuel system
WARNING
 
EWM00060  
Gasoline and its vapors are highly flam-
mable and explosive. Keep away from
sparks, cigarettes, flames, or other 
Standard spark plug:
DPR6EA-9 
1. Spark plug gap
2. Spark plug I.D. mark (NGK) 
Spark plug gap:
0.8–0.9 mm (0.031–0.035 in)
Spark plug torque:
18.0 Nm (13.3 ft-lb) (1.84 kgf-m) 
						

							 
Maintenance 
62 
sources of ignition.
WARNING
 
EWM00910  
Leaking fuel can result in fire or explo-
sion. 
 
Check for fuel leakage regularly. 
 
If any fuel leakage is found, the fuel
system must be repaired by a qualified
mechanic. Improper repairs can make 
the outboard unsafe to operate. 
Check the fuel lines for leaks, crack, or mal-
function. If a problem is found, your Yamaha
dealer or other qualified mechanic should re-
pair it immediately.
Checkpoints 
 
Fuel system parts leakage 
 
Fuel line joint leakage 
 
Fuel line cracks or other damage 
 
Fuel connector leakage 
EMU28980 
Inspecting fuel filter
WARNING
 
EWM00310  
Gasoline is highly flammable, and its va-
pors are flammable and explosive. 
 
If you have any question about properly
doing this procedure, consult your
Yamaha dealer. 
 
Do not perform this procedure on a hot
or running engine. Allow the engine to
cool. 
 
There will be fuel in the fuel filter. Keep
away from sparks, cigarettes, flames or
other sources of ignition. 
 
This procedure will allow some fuel to
spill. Catch fuel in a rag. Wipe up any
spilled fuel immediately. 
 
The fuel filter must be reassembled
carefully with the O-ring, filter cup, and
hoses in place. Improper assembly or
replacement could result in a fuel leak,
which could result in a fire or explosion 
hazard. 
EMU29001 
Cleaning fuel filter 
1. Remove the nut holding the fuel filter as-
sembly if equipped.
ZMU05010
 
1. Nut
ZMU02055
1 
						

							 
Maintenance 
63 
2. Unscrew the filter cup, catching any
spilled fuel in a rag.
3. Remove the filter element, and wash it in
solvent. Allow it to dry. Inspect the filter
element and O-ring to make sure they
are in good condition. Replace them if
necessary. If any water is found in the
fuel, the Yamaha portable fuel tank or
other fuel tanks should be checked and
cleaned.
4. Reinstall the filter element in the cup.
Make sure the O-ring is in position in the
cup. Firmly screw the cup onto the filter
housing.
5. Attach the filter assembly to the bracket
so that the fuel hoses are attached to the
filter assembly.
6. Run the engine and check the filter and
lines for leaks. 
EMU29041 
Inspecting idling speed
WARNING
 
EWM00451  
 
Do not touch or remove electrical parts
when starting or during operation. 
 
Keep hands, hair, and clothes awayfrom the flywheel and other rotating 
parts while the engine is running.
CAUTION:
 
ECM00490  
This procedure must be performed while
the outboard motor is in the water. A
flushing attachment or test tank can be 
used. 
A diagnostic tachometer should be used for
this procedure. Results may vary depending
on whether testing is conducted with the
flushing attachment, in a test tank, or with the
outboard motor in the water.
1. Start the engine and allow it to warm up
fully in neutral until it is running smooth-
ly.
NOTE:
 
Correct idling speed inspection is only possi-
ble if the engine is fully warmed up. If not
warmed up fully, the idle speed will measure
higher than normal. If you have difficulty ver-
ifying the idle speed, or the idle speed re-
quires adjustment, consult a Yamaha dealer 
or other qualified mechanic.
2. Verify whether the idle speed is set to
specification. For idle speed specifica-
tions, see page 48. 
EMU29073 
Changing engine oil
WARNING
 
EWM00760  
 
Avoid draining the engine oil immedi-
ately after stopping the engine. The oil
is hot and should be handled with care
to avoid burns. 
 
Be sure the outboard motor is securely
fastened to the transom or a stable 
1. Filter cup
2. Filter element
3. Filter housing
4. O-ring
ZMU02079
1 4
2
3 
						

							 
Maintenance 
64 
stand.
CAUTION:
 
ECM00970  
 
Do not overfill the oil, and be sure the
outboard motor is upright (not tilted)
when checking and changing the en-
gine oil. 
 
If the oil level is above the upper level
mark, drain until the level meets the
specified capacity. Overfilling the oil 
could cause leakage or damage.
CAUTION:
 
ECM01240  
Change the engine oil after the first 10
hours of operation, and every 100 hours
or at 6-month intervals thereafter. Other- 
wise the engine will wear quickly.
NOTE:
 
Change the engine oil when the oil is still 
warm.
1. Put the outboard motor in an upright po-
sition (not tilted).
2. Prepare a suitable container that holds a
larger amount than the engine oil capac-
ity. Loosen and remove the drain screw
while holding the container under the
drain hole. Then remove the oil filler cap.
Let the oil drain completely. Wipe up any
spilled oil immediately.3. Put a new gasket on the oil drain screw.
Apply a light coat of oil to the gasket and
install the drain screw.
NOTE:
 
If a torque wrench is not available when you
are installing the drain screw, finger tighten
the screw just until the gasket comes into
contact with the surface of the drain hole.
Then tighten 1/4 to 1/2 turn more. Tighten
the drain screw to the correct torque with a 
torque wrench as soon as possible.
4. Add the correct amount of oil through the
filler hole. Install the filler cap.
ZMU02049
 
1. Drain screw 
Drain screw tightening torque:
28.0 Nm (20.7 ft-lb) (2.86 kgf-m)
Recommended engine oil:
4-stroke outboard motor oil
Engine oil quantity (excluding oil filter):
1.0 L (1.06 US qt) (0.88 Imp.qt)
ZMU02056
1