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Need help wit hignition coil testing on 2009 Merc 9.9 4-stroke

T

troutguy

New member

I posted this in the section specific to Mercury but got no answers. So I'll try here.

My 2009 Merc 9.9 4-stroke will not start, and there is no spark on either cylinder. I am checking everything that I can, and now am testing the ignition coil after removing it from the engine. This coil has two wires, orange and black, on the primary side, and two spark plug wires on the secondary side. The black wire on the primary side is normally connected to ground, and I think the orange wire connects to the Electronic Control unit.

For the primary side, the manual's testing procedure shows to measure the resistance between the orange and black wires, and gives a nominal resistance that is very small. I verified that with my ohmmeter so I assume the primary windings are OK. For the secondary side test, the procedure shows to measure the resistance between the end of a spark plug wire and the orange wire on the primary side, and gives a nominal resistance value of just a few ohms. I did that, but instead of a few ohms, I measured an open circuit on all scales of my ohmmeter. This brings up two questions:

1. Why should the nominal resistance be so low (i.e.,a few ohms) for the measurement between the spark plug wire and the orange primary wire?? (I thought the primary and secondary sides would be essentially isolated from each other).

2. Since I measured this as being a very high resistance (an open circuit), does that mean the coil is bad?

Any help you can give me answering either of these two questions would sure be appreciated.
 
Suggest that you post this on the Merc outboard forum on this site. ick on Forum Home at the top left of his page, and click on Mercury Outboards.
 
chawk_man said:
Suggest that you post this on the Merc outboard forum on this site. ick on Forum Home at the top left of his page, and click on Mercury Outboards.
Click to expand...


Thanks, but I did that already and got no response so far, under the Mercury and Mariner heading. But appreciate the response.
 
Okay on the Merc Forum. There is a guy on the Honda forum named Jimmy Dixon who is an expert with small Honda outboards. Not sure what he knows about Merc's, but it's worth a try. His e-mail is [email protected]. Tell him CHawk recommended that you contact him.
 
Just to summarize the outcome of this post, I disconnected each component from the electrical circuit as specified in the repair manual and measured its resistance. The only inconsistency I found was the coil resistance mentioned previously. So I decided I had done everything I could and placed an order for a new coil. After I did that, the engine started great. So the manual was correct, and I shouldn't have questioned it. Thanks also for the help and support provided Chawk and Jim Dixon. :eek:
 
troutguy said:
Just to summarize the outcome of this post, I disconnected each component from the electrical circuit as specified in the repair manual and measured its resistance. The only inconsistency I found was the coil resistance mentioned previously. So I decided I had done everything I could and placed an order for a new coil. After I did that, the engine started great. So the manual was correct, and I shouldn't have questioned it. Thanks also for the help and support provided Chawk and Jim Dixon. :eek:
Click to expand...


I have the same problem on my 9.9 mercury kicker, won't start, tested everything and the only thing I found was the ignition coil resistance reading of the secondary side which is open circuit instead of 8.5 ohm according to the manual. Replaced the coil twice and they are all open cicrcuit now???
Could the ecm fry the coils?

Thanks for your input!
 
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