Filter
Top Products
Maintenance
73
EMU40662
Inspecting 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 check the spark plug be-
cause heat and deposits will cause the spark
plug to slowly break down and erode.
To remove the spark plug
1. Remove the flywheel magnet cover.
2. Remove the ECM (Electronic Control
Module) cover.
3. Remove the bolt that is securing the igni-
tion coil, and then remove the ignition
coil. NOTICE: Do not use any tools to
remove or install the ignition coil. Oth-
erwise, the ignition coil coupler could
be damaged.
[ECM02330]
4. Remove the spark plug. WARNING!
When removing or installing a spark
plug, be careful not to damage the in-
sulator. A damaged insulator could al-
low external sparks, which could lead
to explosion or fire.
[EWM00561]
To check the spark plug
1. Check the condition of the spark plug. If
electrode erosion becomes excessive or
carbon and other deposits are excessive,
replace the spark plug with the specified
plug.
1. Flywheel magnet cover
1. ECM (Electronic Control Module) cover
1
ZMU06971
1
ZMU06947
1. Bolt
2. Ignition coil
2
1
1
2
1
1
1
1
2
2
2
2
ZMU06973
ZMU06948
U6CB10E0.book Page 73 Wednesday, September 30, 2009 9:49 AM