NGK IZFR5J SPARK PLUG

Function and technical context

The NGK IZFR5J spark plug is part of the outboard engine's ignition system, being responsible for generating the electric spark that ignites the fuel and air mixture in the combustion chamber in each work cycle. Its central electrode made of iridium guarantees precise and constant ignition, which directly translates into complete and efficient combustion. Poor ignition due to a bad spark plug causes ignition failures, excessive fuel consumption, notable loss of power and possible damage to the catalyst or the injection system due to unburned fuel. The correct transmission of the spark is also essential for cold starting and engine behavior at low speeds, critical situations in navigation.

When to replace this part?

The most common symptoms that indicate that the spark plug must be changed are: difficult or irregular starts, jerks and losses of speed during acceleration, increased fuel consumption without apparent cause, unstable idle and the presence of black smoke in the exhaust. Iridium spark plugs such as IZFR5J have a longer lifespan than conventional copper ones, but in outboard engines that operate in highly demanding conditions, it is recommended to check them during each seasonal maintenance and replace them preventively according to the engine manufacturer's instructions. Replacing the spark plugs in the shop before the season prevents unexpected breakdowns at sea and ensures maximum engine performance throughout the entire sailing campaign.