Original Factory Mercury Marine Stators

Your outboard stator is the "powerhouse" of your outboards ignition system.
Most Mercury Outboard Stators perform two important functions
1. They provide voltage to your switchbox or CDM's.
2. They charge your vessel's battery(s).

A faulty or failing stator can cause one or more symptoms.
1. Engine fails to run and has no spark.
2. Engine is hard to start especially after sitting from a run.
3. Engine is low on power or has a "miss".
4. Engine stalls frequently.
5. Engine does not recharge the vessel's battery(s).
6. Vessel's battery(s) keep going dead or have too low of voltage.

Stators fail!
Stators can fail for one or more of the following reasons.
1. Age! Old stators fail from internal failures from temperature fluctuations and/or corrosion.
2. Overheating. An engine that is running too hot will "overheat" the stator.
3. Overcharging. Bad batteries, bad battery cables, poor connections and wrong style of batteries can cause the stator to get too hot from attempting to charge the batteries.

Diagnosing your Stator

The procedure for performing an accurate diagnosis on your stator will depend on what model engine you have.

Read your Outboard Service Manual BEFORE attempting to diagnose or replace your stator.

In general, there are two types of tests.
1. Ohms/Resistance Test.
2. Voltage Output Test.

Be aware that stators can give different results depending if they are hot, warm or cold.
Some failures only show up clearly after the motor has reached operating temperature.

Also... Just because a stator passes the "Ohms Test" does not mean it is good.
If a stator fails the Ohms Test, it is bad.
Keep in mind that a bad stator might not be your only problem.
A bad stator can cause a switchbox to fail.

Mercury Marine recommends that the switchbox(s) be replaced in the event of a stator failure.
This is because a bad stator can weaken or ruin a good switchbox.
It is often the case that the old switchbox(s) fail shortly after a new stator has been installed.

To perform the Ohms Test you will need a good ohm meter.
To perform the Voltage Output Test you will need a special DVA Meter.
Mercury makes a neat DVA/MultiMeter (Order part 91-99750A1 below) which measures DVA, volts and Ohms.

ORDER 91-99750A1 DVA Meter Kit $118.00

If any of your specifications are not within the recommended range, the stator is bad.
REMEMBER.... this might not be your only problem but you cannot procede with any more
diagnostics until you are sure you have a good stator.

IMPORTANT: Disconnect your engines batteries and spark plug wires BEFORE attempting to remove your flywheel.
Damage, Injury or Death can result if the engine cranks or starts while you are near the flywheel.
Read your Service Manual for all safety precautions before working on your motor.

Most inline 4 cylinder and V6 Mercury Outboards require a special flwheel removal tool to remove your flywheel.
Check your Service Manual to make sure exactly which tools(s) are required to remove your flywheel.

Order 91-849154T1 Flywheel Removal Tool below (see below for the Flywheel Holding Tool is needed).

ORDER 91-849154T1 Flywheel Removal Tool

Once you have removed the flywheel you will see the stator.
Most Mercury stators or held in place with 4 or more allen head screws.
Use the correct size allen wrench and remove all of the retainer screws.
Remove all the wires from the switch box and the voltage rectifier or regulator/rectifier.

Lift off the old stator and label it with a marker as being "BAD".
You cannot repair and old stator.

Installation is the opposite of removal but make sure to use a drop of LocTite
on the stator screws and flywheel nut as per your Service Manual's recomendation.

Always re-torque all fasteners to factory specifications!

IMPORTANT: Make sure you have properly fastened and grounded your switchboxes BEFORE attempting
to start your motor. An improperly grounded switchbox will fail.

Take extreme care to properly install your flywheel as per your factory shop manual's instructions.
A loose flywheel can cause the engine to run bad, destroy your stator, ruin the crankshaft and/or
fly off and cause damage, injury or death.
You will need a good torque wrench and a good method of holding the flywheel while torquing the nut.
Mercury makes a flywheel holding tool (see below).

ORDER 91-52344 Flywheel Holding Tool $ 166.00

Double-Check all of your connections and fasteners before attempting to start your motor.
Before re-installing your plug wires turn the flywheel by hand to make sure it is not rubbing
the new stator. Make sure all the stator wires are clear of the flywheel so they don't rub.

Properly install your plug wires and battery connections.
Supply a good source of water to the motor using a Flushett and test run the motor.


You will also need your engine's stator specifications.
Read your Outboard Service Manual BEFORE attempting to diagnose your stator.

Replacing Your Stator

First... properly diagnose your ignition before assuming your stator is faulty.
The stator is located under the engine's flywheel.
Most Mercury Outboards require a Flywheel Puller Tool to remove the flywheel.
Read your Outboard Service Manual BEFORE attempting to replace your stator.

We do NOT recommend installing aftermarket parts.