Yamaha F50 Manual

							 
Maintenance 
55 
5. Cooling system flushing is essential to
prevent the cooling system from clog-
ging up with salt, sand, or dirt. In addi-
tion, fogging/lubricating of the engine is
mandatory to prevent excessive engine
damage due to rust. Perform the flush-
ing and fogging at the same time.
WARNING
 
EWM00090  
 
Do not touch or remove electrical parts
when starting or during operation. 
 
Keep hands, hair, and clothes away
from the flywheel and other rotating 
parts while the engine is running.
NOTE:
 
 
When using the flushing attachment,
maintain adequate water pressure and a
steady water flow. 
 
If the overheat warning device is activated,
turn the engine off, and consult your 
Yamaha dealer.
6. Run the engine at a fast idle for a few
minutes in neutral position while supply-
ing fresh water.
7. Just prior to turning off the engine, quick-
ly spray “Yamaha Stor-Rite Engine
Fogging Oil” (Part No. LUB-STRRT-12-
00) alternately into the intake silencer orthe fogging hole of the silencer cover, if
equipped. When properly done, the en-
gine will smoke excessively and almost
stall.
8. Remove the flushing attachment and
wipe off any excess water.
9. Install the top cowling and propeller.
10. Drain the cooling water completely out
of the motor. Clean the body thoroughly.
NOTE:
 
A flushing attachment is available from your 
Yamaha dealer. 
EMU28401 
Lubrication 
1. Grease the spark plug threads and in-
stall the spark plug(s) and torque to
proper specification. For information on
spark plug installation, see page 61.
2. Change the gear oil. For instructions,
see page 68. Inspect the oil for the pres-
ence of water that indicates a leaky seal.
Seal replacement should be performed
by an authorized Yamaha dealer prior to
use.
3. Grease all grease fittings. For further de-
tails, see page 61. 
EMU28421 
Cleaning and anticorrosion 
measures 
1. Wash down the exterior of the outboard
motor with fresh water and dry off com-
pletely.
2. Spray the outboard motor exterior with
“Yamaha Silicone Protectant” (Part No.
LUB-SILCNE-13-00).
3. Wax the cowling with a non-abrasive
wax such as “Yamaha Silicone Wax”
(Part No. ACC-11000-15-02). 
1. Flushing attachment 
						

							 
Maintenance 
56 
EMU28430 
Battery care
WARNING
 
EWM00330  
Battery electrolytic fluid is dangerous; it
contains sulfuric acid and therefore is
poisonous and highly caustic.
Always follow these preventive mea-
sures: 
 
Avoid bodily contact with electrolytic
fluid as it can cause severe burns or
permanent eye injury. 
 
Wear protective eye gear when han-
dling or working near batteries.
Antidote (EXTERNAL): 
 
SKIN - Flush with water. 
 
EYES - Flush with water for 15 minutes
and get immediate medical attention.
Antidote (INTERNAL): 
 
Drink large quantities of water or milk
followed by milk of magnesia, beaten
egg, or vegetable oil. Get immediate
medical attention.
Batteries also generate explosive hydro-
gen gas; therefore, you should always
follow these preventive measures: 
 
Charge batteries in a well-ventilated ar-
ea. 
 
Keep batteries away from fire, sparks,
or open flames (for example: welding
equipment, lighted cigarettes, and so
on.) 
 
DO NOT SMOKE when charging or han-
dling batteries.
KEEP BATTERIES AND ELECTROLYTIC 
FLUID OUT OF REACH OF CHILDREN. 
Batteries vary among manufacturers. There-
fore the following procedures may not al-
ways apply. Consult your battery
manufacturer’s instructions.
Procedure
1. Disconnect and remove the battery from
the boat. Always disconnect the black
negative cable first to prevent the risk of
shorting.
2. Clean the battery casing and terminals.
Fill each cell to the upper level with dis-
tilled water.
3. Store the battery on a level surface in a
cool, dry, well-ventilated place out of di-
rect sunlight.
4. Once a month, check the specific gravity
of the electrolyte and recharge as re-
quired to prolong battery life.
 
EMU28442 
Flushing power unit 
Perform this procedure right after operation
for the most thorough flushing.
CAUTION:
 
ECM01530  
Do not perform this procedure while the
engine is running. The water pump may
be damaged and severe damage from 
overheating can result. 
1. After shutting off the engine, unscrew
the garden hose connector from the fit-
ting on the bottom cowling. 
						

							 
Maintenance 
57 
2. Screw the garden hose adapter onto a
garden hose, which is connected to a
fresh water supply, and then connect it
to the garden hose connector.
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 adapter from the garden hose con-
nector.
4. Reinstall the garden hose connector
onto the fitting on the bottom cowling.
Tighten the connector 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 connector
instead 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 53. 
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 53. 
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 adapter
3. Garden hose connector
1
32
ZMU05096
ZMU02550 
						

							 
Maintenance 
58 
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 
59 
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 (disposable)Inspection / replace-
ment
Fuel system Inspection
Fuel tank (Yamaha por-
table tank)Inspection / cleaning
Gear oil Change
Greasing points Greasing
Idling speed 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
Water pumpInspection / replace-
ment 
						

							 
Maintenance 
60 
EMU28874 
Maintenance chart (additional) 
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
Fuel filter (vapor sepa-
rator tank)Replacement
Anode(s) (exhaust 
cover, cover joint)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 
61 
EMU28931 
Greasing 
Yamaha marine grease (Water resistant grease) 
F50, T50, F60, T60 
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 notattempt 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;
ZMU05087
 
Standard spark plug:
DPR6EB-9 
						

							 
Maintenance 
62 
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 
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 
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)
ZMU05094 
						

							 
Maintenance 
63 
EMU29041 
Inspecting idling speed
WARNING
 
EWM00451  
 
Do not touch or remove electrical parts
when starting or during operation. 
 
Keep hands, hair, and clothes away
from 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 52. 
EMU29073 
Changing engine oil
WARNING
 
EWM00760  
 
Avoid draining the engine oil immedi-
ately after stopping the engine. The oilis hot and should be handled with care
to avoid burns. 
 
Be sure the outboard motor is securely
fastened to the transom or a stable 
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
ZMU03659 
						

							 
Maintenance 
64 
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.5. Start the engine and watch to make sure
the low oil pressure warning indicator (if
equipped) turns off. Make sure that
there are no oil leaks.
CAUTION:
 
ECM00680  
If the low oil pressure warning indicator
does not turn off or if there are oil leaks,
stop the engine and find the cause. Con-
tinued operation with a problem could
cause severe engine damage. Consult
your Yamaha dealer if the problem can- 
not be located and corrected. 
6. Turn off the engine and wait 3 minutes.
Recheck the oil level using the dipstick
to be sure the level falls between the up-
per and lower marks. Fill with oil if it is
below the lower mark, or drain to the
specified level if it is above the upper
mark. 
1. Drain screw 
Drain screw tightening torque:
18.0 Nm (13.3 ft-lb) (1.84 kgf-m)
Recommended engine oil:
4-stroke outboard motor oil
Engine oil quantity (excluding oil filter):
2.5 L (2.64 US qt) (2.20 Imp.qt)
1
ZMU03660
 
1. Oil filler cap
1
ZMU05101