CDI ECU ORIGINAL YAMAHA 6HJ-8591A-00-00

Function and technical context

The CDI ECU with original Yamaha reference 6HJ-8591A-00-00 is the electronic control unit responsible for managing the ignition system of the outboard engine, processing the sensor signals to calculate and execute the optimal ignition advance in each combustion cycle. It works in the engine's electronic ignition system, coordinating the spark of the spark plugs depending on the load, speed and temperature conditions, which is essential to ensure efficient combustion and stable performance. As a genuine Yamaha factory replacement, this CDI ECU is designed and calibrated specifically for F100 series engines, ensuring exact electrical and functional compatibility without the need for reprogramming or adaptation. If the control unit fails, the consequences can range from irregular starts and progressive loss of power to the complete inability to start the engine, leaving the boat without propulsion in potentially dangerous situations. Replacing this component with a genuine Yamaha part ensures that the electronic engine management operates within the exact parameters established by the manufacturer.

When to replace this part?

The most common symptoms of a faulty CDI ECU include intermittent misfires, sudden engine jerks or cuts at certain revolutions, difficulty starting cold or hot, and in advanced cases, the engine shuts down unexpectedly without the possibility of restarting. Unlike wear parts with fixed intervals, the CDI ECU does not have a predefined useful life by working hours, although it is advisable to inspect it and check its connections during each seasonal maintenance, especially on boats exposed to environments with high humidity or vibration. Replacing this unit preventively at the first symptoms of failure avoids being left without propulsion at sea and rules out the ECU as a cause before undertaking more expensive diagnoses on other engine systems.

Equivalent manufacturer part numbers