Mercury Optimax Diagnostic Guide., Page 13Get this manual
OPTIMAX DIAGNOSTIC GUIDE
WARNING
Electrical, ignition and fuel system components on your MercuryMariner outboard are designed and manufactured to comply with USCoast Guard Rules and Regulations to minimize risks of fire and explosionsUse of replacement electrical, ignition or fuel system components, which do not comply with these rules and regulations, could result in fire or explosion hazard and should be avoided
CAUTION
Deep-cycle batteries are not suitable for use as engine starting batteries or for use as accessory batteries that are connected to high output engine charging systemsDeep-cycle battery life may be shortened by high output engine charging systemsRefer to the individual battery maker's instructions for specific battery charging procedures and applications
Procedure 10
SPARK PLUG AND SPARK PLUG WIRES