Cleaning And Adjusting Spark Plug; Checking Fuel Filter - Yamaha F4 Owner's Manual

EMU39291

Cleaning and adjusting spark plug

The spark plug is an important engine compo-
nent. The condition of the spark plug can indi-
cate something about the condition of the
engine. For example, 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 peri-
odically remove and inspect the spark plug
because heat and deposits will cause the
spark plug to slowly break down and erode.
1. Remove the spark plug cap from the
spark plug.
1
1. Spark plug cap
2. Remove the spark plug. If electrode ero-
sion becomes excessive, or if carbon and
other deposits are excessive, you should
replace the spark plug with another of the
correct type. WARNING! When remov-
ing or installing a spark plug, be care-
ful not to damage the insulator. A
damaged insulator could allow exter-
nal sparks, which could lead to explo-
sion or fire.
[EWM00561]
Standard spark plug:
CR6HSB
3. Be sure to use the specified spark plug,
otherwise the engine may not operate
properly. Before fitting the spark plug,
measure the electrode gap with a wire
thickness gauge; replace it if out of spec-
ification.
1. Spark plug gap
2. Spark plug part number
3. Spark plug I.D. mark (NGK)
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
4. When fitting the plug, wipe off any dirt
from the threads, and then screw it in to
the correct torque.
ZMU06803
Spark plug torque:
13.0 Nm (1.33 kgf-m, 9.6 ft-lb)
TIP:
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 finger-
tight. Have the spark plug adjusted to the cor-
rect torque as soon as possible with a torque-
wrench.
EMU39920

Checking fuel filter

The fuel filters are located in the filler hole of
the built-in fuel tank and in the bottom cowling.
Check the fuel filters periodically. If foreign
Maintenance
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