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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10897
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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1979 150hp outboard, will not get over 1700 rpms. just

Customer Question

1979 150hp outboard, will not get over 1700 rpms. just replaced stator unit, and I have a new rectifier I will install soon, that old stator units wiring harness had turned to powder, the 2 yellow wires where the worst.
I tech told me the triggers was the problem, online I saw other petental problems.
what do you think
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
2 1/2 hours no answer?
Customer: replied 1 year ago.
how do I test the power pack?
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

There is no test for the power packs/switch boxes. You can only test the inputs to the switch boxes.

Here are the ohm specs for the trigger and the stator. Your specs for the trigger red and the wires to test in Note 1 in red.

No need in checking the stator as you are replacing it.

The ignition system consists of the stator, trigger, switch boxes and ignition coils. If you have lost spark on 3 cylinders on one side it can be the stator, trigger or switch box. So the 2 concerns you have are the switch boxes and the trigger you are eliminating the stator by replacing it. The ignition coils won't go out on that many cylinders at a time as they are individual components. The switch boxes are the most common failures.

So do the trigger test this will tell you what you need to replace. Trigger or swiotch boxes. Mercury recommends replacing both switch boxes if one has failed.

If the trigger is in spec then replace the switch boxes # *****

Post back with questions.

Customer: replied 1 year ago.
thanks Tan, do I have to remove all the wire to do this?
Expert:  Tan replied 1 year ago.

Yes as this is a resistance test.

Customer: replied 1 year ago.
Thanks Tan,
that test was for the stator, is there a test for the trigger?
Expert:  Tan replied 1 year ago.

That test is for both. If you look all the way to the right of that spec sheet at the top it says trigger. Then it shows see note 1. Which is at the bottom of the page in the red box.

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