Most outboard engines don't require a lot of repairs in their lifetime.  Simple maintenance is usually sufficient for a long-lasting, well-performing engine.  However, one area that you may experience some trouble with is the outboard ignition system.  Most modern outboards use ignition systems consisting of a variety of electrical components.  As you can imagine, any time that there is potential of exposing electrical components to water, there is the potential for damage. Similarly, normal use can eventually wear out some components and require repair.

Troubleshooting an outboard ignition system is not so simple. When people are repairing their outboard's ignition system, one frequent issue we see at Marine Parts Source is that people will end up purchasing several different components trying to guess where the source of the problem is.  We have found that having a better understanding of the entire ignition system and how each component works can help you better understand and identify where issues may be coming from.

Battery
The battery is the source of power for the engine.  It can also be one of the main sources of problems, and is a natural place to start troubleshooting if you aren't getting any power. While a maintenance-free battery like a gel cell or AGM battery are great for running your appliances onboard your vessel, they are not ideal for starting your engine.  Lead-acid batteries are preferable for the job of starting your boat's engine. For outboards, a single 850+ CCA dual-purpose or cranking/starting battery is recommended.  Make sure you charge the battery fully before starting your engine, and never attempt to charge your battery from the stator.

Starter SolenoidsStarter Solenoid
The starter solenoid is basically a relay between the battery and the starter motor.  It is an electromagnet that can receive a large current of electricity from the battery and delivers a large current to the starter, which causes the starter to engage.  If the solenoid receives insufficient current from the battery, it will fail to start the motor and often a rapid clicking sound can be heard. Insufficient current can stem from a low battery, corroded or loose connections or a damaged positive cable from the battery.

 

Outboard StarterStarter
Your boat engine uses the inertia of each cycle to initiate the next cycle. But, before the engine's motion can create this feedback loop, something else must start the engine's motion.  The starter motor turns the flywheel which sets this process in motion.  Starters can drag or wear out over time.  If the starter is receiving enough voltage but the engine is not starting, then it is likely that the starter needs to be replaced.

 

Flywheel
The flywheel is a heavy wheel which maintains the momentum that is first created by the starter and energizes both the stator and the trigger or timer base.  It helps to maintain a smooth and steady engine speed while reducing vibration.

Outboard TriggersTrigger / Timer Base
The trigger or timer base is responsible for sending a signat to the ignition pack letting it know when to fire.  The flywheel contains magnets which pass close to the trigger coils.  When the magnet passes the trigger, the trigger sends a low-voltage signal to the switchbox or ignition pack to fire. Triggers are typically reliable, but they can wear out over time.  The wire insulation can also deteriorate, which will cause the trigger to need to be replaced.

 

Outboard StatorStator
When engaged, the stator provides power to the entire ignition system and the battery charging circuit.  The rotation of the flywheel engages the stator, which is a spinning magnet that creates DC current to power the switchbox or ignition pack  It also passes electricity via the wiring harness to the battery charging ciruit and the fuel injection system.  If you aren't getting spark, the stator could be the culprit.  Similarly, if the battery isn't charging, if the engine is hard to start or if it stalls frequently, the stator could be the cause.  The stator can wear out over time, or it can also be damaged from overheating or overcharging.

Ignition PacksIgnition Pack / Switchbox
The switchbox (for Mercury motors) or the ignition pack (in Johnson/Evinrude motors) provides voltage to the ignition coils.  It stores the voltage supplied by the stator, and then when the signal comes from the trigger, it delivers a charging voltage to the ignition coils.  The switchbox or ignition pack can be tested using a multimeter to verify it is working correctly.

 

Outboard Ignition CoilsIgnition Coil
The ignition coil transforms the voltage received from the ignition pack into a spark voltage of 30,000 to 50,000 volts.  This voltage is used by the spark plugs to ignite the fuel. Coils can become broken or cracked due to overheating, which would require replacing them.  You can also identify that you may have a bad coil if the engine becomes more difficult to start, if there is no spark at the spark plug gap or if the engine misfires.

 

Spark PlugsSpark Plugs
Powered by the voltage from the ignition coil, the spark plug generates a spark across a gap that ignites the fuel, allowing the engine to start and keep running. Some signs of faulty spark plugs are a rough idling engine, trouble starting the engine, a misfiring engine, an engine surging, high fuel consumption and a lack of acceleration.  A bad spark plug can usually be identified just by examining it for blisters, melted electrodes, charring or white deposits.

 

Wiring Harness
Simply put, the wiring harness connects to the electrical components throughout the vessel.  It is particularly important for protecting the boat's wiring from moisture and the harsh marine environment. It carries electricity generatedby the stator to components like the electronic fuel injection module and the rectifier/regulator.

EFI (Electronic Fuel Injection)
The electronic fuel injection (EFI) module controls the supply of fuel to the system. This component ensures that the correct amount of fuel is supplied to start and run the engine, and prevents fuel being used up too quickly.

Rectifier/RegulatorsRectifier / Regulator
The rectifier/regulator controls the voltage of the current produced by the stator.  It also can convert (or rectify) the AC current that is produced into DC current which is usable by the engine's electrical system. When a recitifer/regulator begins failing, the battery can overcharge because the voltage being supplied to it is not being regulated.  Similarly, if you run your engine at high RPMs without a rectifier/regulator, you run the risk of burning out your stator.

 

As you can see, there are a variety of components and possible failure points within an outboard ignition system.  Understanding the function of each component can give you a starting point for where to troubleshoot.  If you have more detailed questions about troubleshooting your engine's ignition system, feel free to give our ABYC-certified experts a call at (866)388-0390.