How to Test Mercury Optimax Outboard Starter


What are the correct inspection procedures to determine if the device for starting my 2006 90hp Mercury Optimax boat motor is faulty or not? The starter motor does not turn but the battery is good.

Actually is there a way to check if the starter motor is bad or if it’s the starter solenoid that might be defective?

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Vernon 2 years 2020-12-10T18:05:28+00:00 4 Answers 568 views Beginner 2

Answers ( 5 )


    First perform an assessment of the following conditions before you run a test on the starter.

    1. Establish whether or not the battery is fully charged.
    2. Be certain that the control lever is in the neutral position when starting the Mercury Optimax.
    3. Examine the battery terminals for loose connections or excessive corrosion.
    4. Check if the 20 amp fuse is blown.
    5. Check starter, battery and charging system wires for worn insulation or frayed wires.

    To test the starter you will need to get this, I’m sure you already own it.

    How to Test Starter Motor

    [a] To alternator. [b] Starter. [c] Starter Solenoid. [d] Neutral start switch – located in control box. [e] Ignition switch. [f] 20 ampere fuse. [g] Slave solenoid. [h] Battery.

    Put the ignition key in and turn it to the START position and check for voltage at #1 test point. What happen?

    A. Did the multimeter indicate voltage and did the solenoid click?
    B. Was there no voltage at all?
    C. Did the meter indicate voltage and the solenoid does not click?

    Let me know what happen.

    Best answer

    Yes there is voltage and the solenoid clicks.


      Check voltage at test point #9. If the voltage is greater than 9.5 volts the starter motor is defective.

      If voltage at test point #9 is below 9.5 volts then the starter solenoid is faulty.


    Hello, sorry to intrude on your conversation but, I tested #1, what happens if you have voltage and the solenoid does not click? My engine is a 2004 Mercury Optimax 115hp.


      Then you should check for starter motor ground at test point 10. If the ground is good it means the starter solenoid is faulty. Otherwise I would suspect a bad ground, in which case you should either try cleaning the cable ends, check for tightness or replace them.

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