Maintenance

EMU40662

Inspecting spark plug

The spark plug is an important engine compo- nent. The condition of the spark plug can indicate 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 periodically remove and check the spark plug because 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.

1

ZMU06971

1.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]

1

 

2

 

1

1

2

2

1

1

2

2

 

1

2

ZMU06973

1.Bolt

2.Ignition coil

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]

1

ZMU06947

1. ECM (Electronic Control Module) cover

ZMU06948

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.

73