Yamaha F4 Owner's Manual

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Contents

Maintenance58EMU39291Cleaning and adjusting spark plugThe spark plug is an important engine compo-nent. The condition of the spark plug can indi-cate something about the condition of theengine. For example, if the center electrodeporcelain is very white, this could indicate anintake air leak or carburetion problem in thatcylinder. Do not attempt to diagnose anyproblems yourself. Instead, take the outboardmotor to a Yamaha dealer. You should peri-odically remove and inspect the spark plugbecause heat and deposits will cause thespark plug to slowly break down and erode.1. Remove the spark plug cap from thespark plug.2. Remove the spark plug. If electrode ero-sion becomes excessive, or if carbon andother deposits are excessive, you shouldreplace the spark plug with another of thecorrect type. WARNING! When remov-ing or installing a spark plug, be care-ful not to damage the insulator. Adamaged insulator could allow exter-nal sparks, which could lead to explo-sion or fire. [EWM00561]3. Be sure to use the specified spark plug,otherwise the engine may not operateproperly. Before fitting the spark plug,measure the electrode gap with a wirethickness gauge; replace it if out of spec-ification.4. When fitting the plug, wipe off any dirtfrom the threads, and then screw it in tothe correct torque.TIP:If a torque-wrench is not available when youare fitting a spark plug, a good estimate of thecorrect 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.EMU39920Checking fuel filterThe fuel filters are located in the filler hole ofthe built-in fuel tank and in the bottom cowling.Check the fuel filters periodically. If foreign1. Spark plug capStandard spark plug:CR6HSBZMU0680311. Spark plug gap2. Spark plug part number3. Spark plug I.D. mark (NGK)Spark plug gap:0.6–0.7 mm (0.024–0.028 in)Spark plug torque:13.0 Nm (1.33 kgf-m, 9.6 ft-lb)