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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14580
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I am reading through your thread: and have some questions.

Customer Question

Hello Jason, I am reading through your thread: and have some questions.
JA: Thanks. Can you give me any more details about your issue?
Customer: Mercury 9.9 circa 80's / 90's ( the serial number sticker is there but the serial number it self is gone) Long shaft, i just got it a week ago and it was left half sitting in the water for 5 years or so, lower was covered in barnacles. I rebuilt the water pump and replaced the impeller. did the lower oil plugs, gas filfer
JA: OK got it. Last thing — Marine Mechanics generally expect a deposit of about $26 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 12 months ago.
Category: Boat
Expert:  Jason replied 12 months ago.

Hello, this is Jason, whom am I speaking with?

How can I help you?

Expert:  Jason replied 12 months ago.

It looks like you read my response and logged off. Did you still need help with the engine?

Customer: replied 11 months ago.
Hey Jason, sorry for the long silence. I got distracted with other projects:
To refresh you, Mercury 9.9 2 stroke I believe the serial number is:
OG187500 (it is completely faded and that is my best guess)
it sat for years before i got it and i did a bunch of work on it, it ran for 5 minutes and then stalled.
No Spark
remote electric starter
disconnecting the black and yellow did not yield a spark.
I ran the tests with my digital multimeter from this thread:
Black sator test results in order from the worksheet in Ohms:
If my math is correct, allowing for the R x 100 for the second two tests i should be good here, although the last test is a little low, I am not sure if that could be the failure point.Next, I ran the Trigger test:
I got .686 and again if my math is correct for the R x 100 it should be all set?Please advise / should I test the coils next?~Scott
Expert:  Jason replied 11 months ago.

Hi Scott. Did you measure between the black/yellow and black on the stator? When you did these tests, did you disconnect the stator from the switchbox first?

Customer: replied 11 months ago.
the table said to use ground for the black wire on the first two tests. I used the spark plug threads for ground.
I have the throttle assembly / starter cables disconnected and had both the black/white and black/yellow wires disconnected for the tests.
I do not believe I have the sator and switchbox disconnected.
Expert:  Jason replied 11 months ago.

When it come to resistance measurments you would need to disconnect and isolate the components first. So If you are going to measure the stator and trigger outputs, you must disconnect them from the switchbox first. Does that make sense?

Expert:  Jason replied 11 months ago.

Do you want to re-check everything with the components disconnected and get back to me?

Customer: replied 11 months ago.
Expert:  Jason replied 11 months ago.

Okay let me know what happens.

Customer: replied 11 months ago.
I removed the pull cord assembly, how do i get the fly wheel off?
Expert:  Jason replied 11 months ago.

Is there a reason you need to pull the flywheel off? Did the stator or trigger test bad?

Customer: replied 11 months ago.
well, on that original thread i am following you mention that removing the flywheel is necessary.
So, if that is not the case, I could try to disconnect the two from the next components. I do not have the rest of the diagram so i am unsure what they are called.
Expert:  Jason replied 11 months ago.

What you want to do is follow the wires that come out from underneath of the flywheel, they will run to the switchbox. Disconnect the stator and trigger wires from the flywheel and meausure their resistances again. If either the stator or trigger fails their resistance test, replace that part. If they both pass, replace the switchbox. Does that make sense?

Customer: replied 11 months ago.
I am seeing what appears to be a third component under the wheel.
I disconnected this from a small box on the side of the motor.
What I think is the satir appears to only have one cable assembly coming out of it. Black/white and black/yellow and I just got almost identical results:
After disconnecting what I assume was the fly wheel cable? From this unknown box the trigger read .728
Customer: replied 11 months ago.
Jason, three sets of wires come out of the flywheel.
Two sets run to connectors that go through a box, these appear to be the sator and trigger.
The third appears to go to this other component, I am guessing this is the switchbox?
All three are disconnected.
The results are above, please advise
Expert:  Jason replied 11 months ago.

I can't see much in your pictures. Do you have a black with a yellow strip wire coming out from under the flywheel, or no?

Expert:  Jason replied 11 months ago.

Good morning, just checking in. How are you making out?

Customer: replied 11 months ago.
Hey Jason,
So, I cannot disconnect anything else from under the fly wheel.
the readings came out similar when i did the one disconnect i could find.
So unless you can tell me differently, it looks like both the sator and trigger are bad, coming in with Way too much resistance.I tested both the coil packs, and though I do not know what they are supposed to read, the readings are similar at .970 and .980 so i am assuming they are fine.I am thinking i should replace the two components under the fly wheel.
Expert:  Jason replied 11 months ago.

Can you take a couple of pictures of the engine from far out and from a few different angles so I can see exactly what this is. You said it was a 9.9 horsepower but when I run the serial number you gave me it comes up a 25.

Expert:  Jason replied 10 months ago.

Any luck with a few pictures?

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