No spark on any of the coils

Joined
Oct 6, 2015
Messages
3
I have a 2003 mercury 90hp, this boat gets used a lot and has been very trouble free. Last week end I went to crank it and it would not start. The engine turns over fine but none of the coils are making spark. The engine does not have a kill switch, connections appear to be good. does anyone have an idea what could cause all three coils not to fire.
 

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Go to your motor on the CDI link provided in my signature. It will give you great step by step procedures to figure out where the issue is.

All engines have a kill circuit (May not be a safety cut off) but in order to cut the motor off with the key it has to activate the kill circuit. Disconnect the black/yellow wire from the switchbox and see if spark returns.
 
Last edited:

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Sure thing.

Just be sure to fill us in whether you found your issue or not. Don't leave us hangin!!
 
Joined
Oct 6, 2015
Messages
3
Just wanted to let you know, had some time to work on it yesterday. I unplugged the yellow and black wire where in turns from one wire to three and heads to all three coils and it started up and ran fine. Curiously I could not turn the engine off with the wire disconnected (expected that) but when I plugged the wire back in it did not quit running (like I expected). after I plugged it back in it did turn off with the key. It appears to be working fine now turns on and off with the key. I plan on taking out this weekend and it gives me peace of mind knowing exactly what wire to unplug if it does it again. I know I have not really fixed anything and it will more than likely do it again. I am thinking its the wire going to the switch or maybe the switch itself.
 

DavidMoore

Petty Officer 2nd Class
Joined
Jun 2, 2015
Messages
183
Glad you know what the problem is but please, if you have an open boat, get a kill switch sorted and use it.
It may one day save your life or the life of someone else.

Apologies if I misunderstood.
 
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