Yamaha F150 Four Stroke Manual

Maintenance
44
ging 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.
EMU28400Lubrication (except oil injection 
models)
1. Grease the spark plug threads and install
the spark plug(s) and...

Maintenance
45
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.
EMU28441Flushing power unit...

Maintenance
46
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 until
it is completely out of the water will achieve
better results.

For cooling system flushing instructions,
see page 42.
EMU28450Cleaning the outboard motor
After use, wash the exterior of the outboard
motor with fresh water. Flush the cooling sys-
tem with fresh water.
NOTE:
For...

Maintenance
47
EMU30562Maintenance chart
NOTE:

Refer to the sections in this chapter for explanations of each owner-specific action.

The maintenance cycle on these charts assume usage of 200 hours per year and regular
flushing of the cooling water passages. Maintenance frequency should be adjusted accord-
ing to usage conditions.

Disassembly or repairs may be necessary depending on the outcome of maintenance
checks.

Expendable or consumable parts and lubricants will lose their effectiveness over time...

Maintenance
48
EMU28874Maintenance chart (additional)
EMU28910
NOTE:
When using lead or high-sulfur gasoline, inspecting valve clearance may be required more fre-
quently than every 500 hours.
Throttle link / throttle 
cable / throttle pick-up 
timingInspection / adjustment
Water pumpInspection / replace-
ment
Engine oil Inspection / change
Oil filter (cartridge) Change
Spark plug(s)Cleaning / adjustment / 
replacement
Timing beltInspection / replace-
ment
Item ActionsEvery
500 hours (2.5 years) 1000...

Maintenance
49
EMU28931Greasing
Yamaha marine grease (Water resistant grease)
EMU28952Cleaning 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 compo-
nent and is easy to inspect. The condition of
the spark plug can indicate something about
the condition of the engine. For example, if the
center electrode...

Maintenance
50
spark plug because heat and deposits will
cause the spark plug to slowly break down
and erode. If electrode erosion becomes ex-
cessive, or if carbon and other deposits are
excessive, you should replace the spark plug
with another of the correct 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 gasket
surface and use a new gasket. Wipe off any
dirt from the...

Maintenance
51
Checkpoints

Fuel system parts leakage

Fuel line joint leakage

Fuel line cracks or other damage

Fuel connector leakageEMU28980Inspecting 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,...

Maintenance
52
4. Install the filter element and filter cup into
the filter housing.
5. Tighten the ring nut so that one of the
larger ring nut tabs is aligned with the lock
tab.
6. Run the engine and check the filter and
lines for leaks.
NOTE:
If any water is in the fuel, the red ring in the
fuel filter unit will float. If so, remove the cup
and drain the water.
EMU29073Changing engine oil
WARNING
EWM00760

Avoid draining the engine oil immediate-
ly after stopping the engine. The oil is
hot and should...

Maintenance
53
2. Prepare a suitable container that holds a
larger amount than the engine oil capaci-
ty. 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...