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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10964
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have late 80 150 two stroke motor plugs not fireing on

Customer Question

I have late 80 150 two stroke motor plugs not fireing on left side if your standing at back of motor
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

This can be one of 3 things switch box, stator or trigger. Swap the switch boxes. If the misfiring cylinders move then we know you have a bad switch box. If the misfiring cylinders stay then you have a bad stator or bad trigger. Most common failure is switch box. Then stator and finally trigger. Now we can do an ohm test of the stator and the trigger as a test. If the trigger or stator fail the ohm test we know which component is bad. The ohm test can read good and the component can still be bad this requires testing with a DVA adapter or peak reading volt meter to check actual voltage out put of each of the components. There is no test for the switch boxes.

So do the switch box swap then post back with findings. If the misfire moves then the switch box is bad. Replace the switch boxes as a pair. Post back if the misfiring cylinders don't move. I will need the engine serial number to get the correct specs for the ohm test of the stator and trigger.

Post back with questions and findings.

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