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Mercury 8hp top cylinder no spark

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Hey guys.  

I recently picked up a 90s Merc as another motor project to pass the time with this covid.  I knew it wasn't running, great. Hard to start and if it did it would misfire and studder.   Changed up the carb gaskets, needle, float(had some gas in it).   Thought it was the float was being weighed down so it was not getting right amount of fuel.  Diaphragm was a bit stiff and the plunger was leaking gas.  So all that was changed but still won't start.   Checked for spark again and the top cylinder no longer has spark.  I guess it was going which could explain the misfire.   Had it running good at one time but it just cut out with no warning so I'm assuming the spark cut out at that point. 

So looking for a bit of help for any of you Merc owners.  I want to om test the spark wire but I can not for the life of me figure out how to get it out of the ignition coil. Johnson's are much easier.  I also noticed the lip of the coil where the spark plug wire attaches to is cracked and a small piece of off.   Would that affect spark?    Any suggestions?    Electrical is new to me.   All my past issues have mostly been gas related.  So any tips would be appreciated.  

Thank you in advance



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Symptoms of a Bad Coil on an Outboard Motor

If your coil does go bad, there are several symptoms you might notice.

Engine Experiences a Hard Starting Condition

When the coil becomes weakened and damaged, it is unable to produce the energy that it once did.

What you are left with is a weaker spark at the plug gap, which makes it more difficult to start the engine. If you regularly foul the spark plugs, this is one indication that your boat is suffering from a weak spark.

If the engine takes a little bit longer to fire up when turning the key and getting the engine to turn over. This is another sign of possibly a bad coil, or missing spark on one cylinder.

Cracked or Broken Coil

Like everything that is on a boat engine, the coil inside your outboard is sealed component. To run properly, the coil must remain intact and crack-free.

If you examine the coil and find it is cracked or looks melted. This is a sign that the coil has gotten, hot, shorted, or overheated at some point in time. Anytime this is noticed, you must replace the coil.

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Thanks for the replies.   So looks like I'll have to get a new coil. Still can't figure out how to remove the spark plus wire from the coil.   Any thoughts?   Am I just not yanking hard enough? 


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So I got it out but at the expense of the plug wire.  

So I'm doing an ohm test on the coil. On the Positive and neg posts I'm getting 0.7.   From negative to the coil socket I'm getting 962.   Looks like I should be getting 1280 to 1480.   So is this coil junk? 

Sorry for all the questions. Really appreciate the feedback.   Just try g to learn here 




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An update. 

There are 2 lines coming from the power pack to the coils.   I decided to put one the line going to the coil that is not sparking to the good coil and there is no spark. So now I think it's either a power pack issue or stator or something else.   Looks like I need to research further. 

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Buy both coils and you'll find out what they come with re wires. If one coil overheated to crack the other may be a close second. Also check the impeller since overheating and bad impellers go hand in hand.  

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