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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1975 stinger 75hp outboard motor. It is a 3

Customer Question

I have a 1975 Johnson stinger 75hp outboard motor. It is a 3 cylinder motor and only firing on 2 cylinders. It doesn't run right nor idle correctly. The marina in town thought it was the "brain box" but it tested good so told me it was a trigger. I'm not familiar with boat motors but am a diesel mechanic. Is there any way to test this
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

Yes there is an ohm test and a cranking test. The cranking test is the most accurate but require a peak reading volt meter or a DVA adapter for your volt meter.

There is also a test we can do that will tell us if the trigger is firing by swapping the wires around. The trigger has 3 colored wires and a common. You will need a spark gap tester for this check. First check that you have spark. If you have spark on all cylinder then you don't have an ignition issue. Now have you done a compression test? Do you have a spark gap tester?

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