Yamaha F50 Manual

							 
Maintenance 
65 
7. Dispose of used oil according to local
regulations.
NOTE:
 
 
For more information on the disposal of
used oil, consult your Yamaha dealer. 
 
Change the oil more often when operating
the engine under adverse conditions such 
as extended trolling. 
EMU29112 
Checking wiring and connectors 
 
Check that each grounding wire is properly
secured. 
 
Check that each connector is engaged se-
curely. 
EMU29120 
Exhaust leakage 
Start the engine and check that no exhaust
leaks from the joints between the exhaust
cover, cylinder head, and body cylinder. 
EMU29130 
Water leakage 
Start the engine and check that no water
leaks from the joints between the exhaust
cover, cylinder head, and body cylinder. 
EMU29140 
Engine oil leakage 
Check for oil leaks on the around the engine.
NOTE:
 
If any leaks are found, consult your Yamaha 
dealer. 
EMU29163 
Checking power trim and tilt / power 
tilt system
WARNING
 
EWM00430  
 
Never get under the lower unit while it
is tilted, even when the tilt support lever
is locked. Severe injury could occur if
the outboard motor accidentally falls. 
 
Make sure no one is under the outboard 
motor before performing this test. 
1. Check the power trim and tilt unit / power
tilt unit for any sign of oil leaks.
2. Operate each of the power trim and tilt
switches / power tilt switches to check
that all switches work.
3. Tilt the outboard motor up and check
that the trim and tilt rod / the tilt rod is
pushed out completely.
4. Check that the trim and tilt rod / the tilt
rod is free of corrosion or other flaws.
5. Tilt the outboard motor down. Check
that the trim and tilt rod / the tilt rod oper-
ates smoothly. 
1. Lower level mark
2. Oil dipstick
3. Upper level mark
132
ZMU05091
 
1. Trim and tilt rod
1
ZMU03662 
						

							 
Maintenance 
66
NOTE:
 
Consult your Yamaha dealer if any operation 
is abnormal. 
EMU29171 
Checking propeller
WARNING
 
EWM00321  
You could be seriously injured if the en-
gine accidentally starts when you are
near the propeller. 
 
Before inspecting, removing, or install-
ing the propeller, remove the spark
plug caps from the spark plugs. Also,
place the shift control in neutral, turn
the main switch to “” (off) and re-
move the key, and remove the lanyard
from the engine stop switch. Turn off
the battery cut-off switch if your boat
has one. 
 
Do not use your hand to hold the pro-
peller when loosening or tightening the
propeller nut. Put a wood block be-
tween the anti-cavitation plate and the
propeller to prevent the propeller from 
turning. 
Checkpoints 
 
Check each of the propeller blades for
wear, erosion from cavitation or ventila-
tion, or other damage. 
 
Check the propeller shaft for damage. 
 
Check the splines / shear pin for wear or
damage. 
 
Check for fish line tangled around the pro-
peller shaft. 
 
Check the propeller shaft oil seal for dam-
age.
NOTE:
 
If the shear pin equipped: it is designed to
break if the propeller hits a hard underwater
obstacle to help protect the propeller and
drive mechanism. The propeller will then
spin freely on the shaft. If this happens, the 
shear pin must be replaced.
ZMU03663
ZMU01897 
						

							 
Maintenance 
67 
EMU30660 
Removing the propeller 
EMU29194 
Spline models 
1. Straighten the cotter pin and pull it out
using a pair of pliers.
2. Remove the propeller nut, washer, and
spacer (if equipped).3. Remove the propeller and thrust wash-
er. 
EMU30670 
Installing the Propeller 
EMU29231 
Spline models
CAUTION:
 
ECM00340  
 
Be sure to install the thrust washer be-
fore installing the propeller, otherwise
the lower case and propeller boss
could be damaged. 
 
Be sure to use a new cotter pin and
bend the ends over securely. Otherwise
the propeller could come off during op- 
eration and be lost. 
1. Apply Yamaha marine grease or a cor-
rosion resistant grease to the propeller
shaft.
2. Install the spacer (if equipped), thrust
washer, and propeller on the propeller
shaft.
3. Install the spacer (if equipped) and the
washer. Tighten the propeller nut to the
specified torque.
4. Align the propeller nut with the propeller
shaft hole. Insert a new cotter pin in the
hole and bend the cotter pin ends.
NOTE:
 
If the propeller nut does not align with the
propeller shaft hole after tightening to the 
1. Cotter pin
2. Propeller nut
3. Washer
4. Spacer
5. Propeller
6. Thrust washer
1. Cotter pin
2. Propeller nut
3. Washer
4. Spacer
5. Propeller
6. Thrust washer
ZMU03228
1
2 3
4
5 6
ZMU02063 
						

							 
Maintenance 
68 
specified torque, tighten the nut further to 
align it with the hole. 
EMU29282 
Changing gear oil
WARNING
 
EWM00800  
 
Be sure the outboard motor is securely
fastened to the transom or a stable
stand. You could be severely injured if
the outboard motor falls on you. 
 
Never get under the lower unit while it
is tilted, even when the tilt support lever
or knob is locked. Severe injury could
occur if the outboard motor accidental- 
ly falls. 
1. Tilt the outboard motor so that the gear
oil drain screw is at the lowest point pos-
sible.
2. Place a suitable container under the
gear case.
3. Remove the gear oil drain screw and
gasket.
NOTE:
 
 
If a magnetic gear oil drain screw is
equipped, remove all metal particles from
the screw before installing it. 
 
Always use new gaskets. Do not reuse the 
removed gaskets.
4. Remove the oil level plug and gasket to
allow the oil to drain completely.
CAUTION:
 
ECM00710  
Inspect the used oil after it has been
drained. If the oil is milky, water is getting
into the gear case which can cause gear
damage. Consult a Yamaha dealer for re- 
pair of the lower unit seals.
NOTE:
 
For disposal of used oil, consult your 
Yamaha dealer.
5. With the outboard motor in a vertical po-
sition, and using a flexible or pressur-
ized filling device, inject the gear oil into
the gear oil drain screw hole. 
1. Gear oil drain screw
2. Oil level plug
ZMU03273
2
1
 
Recommended gear oil:
Hypoid gear oil SAE#90
Gear oil quantity:
F50TR 430.0 cm 
3
 
 (14.54 US oz) 
(15.17 Imp.oz)
F60TR 430.0 cm 
3
 
 (14.54 US oz) 
(15.17 Imp.oz)
T50TR 670.0 cm 
3
 
 (22.65 US oz) 
(23.63 Imp.oz)
T60TR 670.0 cm 
3
 
 (22.65 US oz) 
(23.63 Imp.oz)
ZMU03274 
						

							 
Maintenance 
69 
6. Put a new gasket on the oil level plug.
When the oil begins to flow out of the oil
level plug hole, insert and tighten the oil
level plug.
7. Put a new gasket on the gear oil drain
screw. Insert and tighten the gear oil
drain screw. 
EMU29302 
Cleaning fuel tank
WARNING
 
EWM00920  
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. 
 
Keep away from sparks, cigarettes,
flames, or other sources of ignition
when cleaning the fuel tank. 
 
Remove the fuel tank from the boat be-
fore cleaning it. Work only outdoors in
an area with good ventilation. 
 
Wipe up any spilled fuel immediately. 
 
Reassemble the fuel tank carefully. Im-
proper assembly can result in a fuel
leak, which could result in a fire or ex-
plosion hazard. 
 
Dispose of old gasoline according to lo- 
cal regulations. 
1. Empty the fuel tank into an approved
container.
2. Pour a small amount of suitable solvent
into the tank. Install the cap and shake
the tank. Drain the solvent completely.3. Remove the screws holding the fuel joint
assembly. Pull the assembly out of the
tank.
4. Clean the filter (located on the end of the
suction pipe) in a suitable cleaning sol-
vent. Allow the filter to dry.
5. Replace the gasket with a new one. Re-
install the fuel joint assembly and tighten
the screws firmly. 
EMU29312 
Inspecting and replacing anode(s) 
Yamaha outboard motors are protected from
ZMU03231
ZMU02324 
						

							 
Maintenance 
70 
corrosion by sacrificial anodes. Inspect the
external anodes periodically. Remove scales
from the surfaces of the anodes. Consult a
Yamaha dealer for replacement of external
anodes.
CAUTION:
 
ECM00720  
Do not paint anodes, as this would render 
them ineffective.
NOTE:
 
Inspect ground leads attached to external
anodes on equipped models. Consult a
Yamaha dealer for inspection and replace-
ment of internal anodes attached to the pow- 
er unit. 
EMU29320 
Checking battery (for electric start 
models)
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
ZMU04721
ZMU03664
ZMU04722 
						

							 
Maintenance 
71 
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.
CAUTION:
 
ECM00360  
 
A poorly maintained battery will quickly
deteriorate. 
 
Ordinary tap water contains minerals
harmful to a battery, and should not be 
used for topping up. 
1. Check the electrolyte level at least once
a month. Fill to the manufacturer’s rec-
ommended level when necessary. Top
up only with distilled water (or pure de-
ionized water suitable to use in batter-
ies).
2. Always keep the battery in a good state
of charge. Installing a voltmeter will help
you monitor your battery. If you will not
use the boat for a month or more, re-
move the battery from the boat and store
it in a cool, dark place. Completely re-
charge the battery before using it.
3. If the battery will be stored for longer
than a month, check the specific gravity
of the fluid at least once a month and re-
charge the battery when it is low.
NOTE:
 
Consult a Yamaha dealer when charging or 
re-charging batteries. 
EMU29331 
Connecting the battery
WARNING
 
EWM00570  
Mount the battery holder securely in a
dry, well-ventilated, vibration-free loca-
tion in the boat. Install a fully charged bat- 
tery in the holder.
CAUTION:
 
ECM01121  
 
Make sure the main switch (on applica-
ble models) is “” (off) before work-
ing on the battery. 
 
Reversal of the battery cables will dam-
age the electrical parts. 
 
Connect the red battery cable first
when installing the battery and discon-
nect the black battery cable first when
removing it. Otherwise, the electrical
parts can be damaged. 
 
The electrical contacts of the battery
and cables must be clean and properly
connected, or the battery will not start 
the engine. 
Connect the red battery cable to the POSI-
TIVE (+) terminal first. Then connect the
black battery cable to the NEGATIVE (-) ter-
minal. 
						

							 
Maintenance 
72 
EMU29370 
Disconnecting the battery 
Disconnect the BLACK cable from the NEG-
ATIVE (-) terminal first. Then disconnect the
RED cable from the POSITIVE (+) terminal. 
EMU29390 
Checking top cowling 
Check the fitting of the top cowling by push-
ing it with both hands. If it is loose have it re-
paired by your Yamaha dealer. 
EMU29400 
Coating the boat bottom 
A clean hull improves boat performance. The
boat bottom should be kept as clean of ma-
rine growth as possible. If necessary, the
boat bottom can be coated with an anti-foul-
ing paint approved for your area to inhibit
marine growth.Do not use anti-fouling paint which includes
copper or graphite. These paints can cause
more rapid engine corrosion. 
1. Red cable
2. Black cable
3. Battery
ZMU01943 
						

							 
73 
Trouble Recovery 
EMU29424 
Troubleshooting 
A problem in the fuel, compression, or igni-
tion systems can cause poor starting, loss of
power, or other problems. This section de-
scribes basic checks and possible remedies,
and covers all Yamaha outboard motors.
Therefore some items may not apply to your
model.
If your outboard motor requires repair, bring
it to your Yamaha dealer.
If the engine trouble warning indicator is
flashing, consult your Yamaha dealer. 
Starter will not operate. 
Q. Is battery capacity weak or low?
A. Check battery condition. Use battery of
recommended capacity.
Q. Are battery connections loose or corrod-
ed?
A. Tighten battery cables and clean battery
terminals.
Q. Is fuse for electric start relay or electric cir-
cuit blown?
A. Check for cause of electric overload and
repair. Replace fuse with one of correct am-
perage.
Q. Are starter components faulty?
A. Have serviced by a Yamaha dealer.
Q. Is shift lever in gear?
A. Shift to neutral. 
Engine will not start (starter operates). 
Q. Is fuel tank empty?
A. Fill tank with clean, fresh fuel.
Q. Is fuel contaminated or stale?A. Fill tank with clean, fresh fuel.
Q. Is fuel filter clogged?
A. Clean or replace filter.
Q. Is starting procedure incorrect?
A. See page 39.
Q. Has fuel pump malfunctioned?
A. Have serviced by a Yamaha dealer.
Q. Are spark plug(s) fouled or of incorrect
type?
A. Inspect spark plug(s). Clean or replace
with recommended type.
Q. Are spark plug cap(s) fitted incorrectly?
A. Check and re-fit cap(s).
Q. Is ignition wiring damaged or poorly con-
nected?
A. Check wires for wear or breaks. Tighten
all loose connections. Replace worn or bro-
ken wires.
Q. Are ignition parts faulty?
A. Have serviced by a Yamaha dealer.
Q. Is engine stop switch lanyard not at-
tached?
A. Attach lanyard.
Q. Are engine inner parts damaged?
A. Have serviced by a Yamaha dealer. 
Engine idles irregularly or stalls. 
Q. Are spark plug(s) fouled or of incorrect
type?
A. Inspect spark plug(s). Clean or replace
with recommended type. 
						

							 
Trouble Recovery 
74 
Q. Is fuel system obstructed?
A. Check for pinched or kinked fuel line or
other obstructions in fuel system.
Q. Is fuel contaminated or stale?
A. Fill tank with clean, fresh fuel.
Q. Is fuel filter clogged?
A. Clean or replace filter.
Q. Have ignition parts failed?
A. Have serviced by a Yamaha dealer.
Q. Has warning system activated?
A. Find and correct cause of warning.
Q. Is spark plug gap incorrect?
A. Inspect and adjust as specified.
Q. Is ignition wiring damaged or poorly con-
nected?
A. Check wires for wear or breaks. Tighten
all loose connections. Replace worn or bro-
ken wires.
Q. Is specified engine oil not being used?
A. Check and replace oil as specified.
Q. Is thermostat faulty or clogged?
A. Have serviced by a Yamaha dealer.
Q. Are carburetor adjustments incorrect?
A. Have serviced by a Yamaha dealer.
Q. Is fuel pump damaged?
A. Have serviced by a Yamaha dealer.
Q. Is air vent screw on fuel tank closed?
A. Open air vent screw.
Q. Is choke knob pulled out?A. Return to home position.
Q. Is motor angle too high?
A. Return to normal operating position.
 
Q. Is carburetor clogged?
A. Have serviced by a Yamaha dealer.
Q. Is fuel joint connection incorrect?
A. Connect correctly.
Q. Is throttle valve adjustment incorrect?
A. Have serviced by a Yamaha dealer.
Q. Is battery cable disconnected?
A. Connect securely. 
Warning buzzer sounds or indicator
lights. 
Q. Is cooling system clogged?
A. Check water intake for restriction.
Q. Is engine oil level low?
A. Fill oil tank with specified engine oil.
Q. Is heat range of spark plug incorrect?
A. Inspect spark plug and replace it with rec-
ommended type.
Q. Is specified engine oil not being used?
A. Check and replace oil with specified type.
Q. Is engine oil contaminated or deteriorat-
ed?
A. Replace oil with fresh, specified type.
Q. Is oil filter clogged?
A. Have serviced by a Yamaha dealer.
Q. Has oil feed/injection pump malfunc-
tioned?