1979 mercury 115 hp no spark to any cylinders

asjeep

Recruit
Joined
May 13, 2011
Messages
5
Hello,

I bought a boat (1983 4 winns) on it was a 1979 mercury 115 6 cylinder.


The previous owner had some issues apparently and seems to have not had a degree in electrical repair.... to say the least :)

anyways we have replaced the yellow/red stator wires and now are getting electricity down to the switch's when turning the motor over no electricity coming out of the other side of the switch (headed towards the coils) thus no spark at the spark plugs....


Please take a look at the linked pictures and you will see where the wiring has been butchered by the previous owner, some rewired by us.

Also according to the wiring diagram form maxrules.com it appears that I am missing an "idle stabilizer" box that is nowhere to be found assuming the diagram is correct of course.....

Any help is much appreciated

https://picasaweb.google.com/acbaldwi/1979Mercury115?feat=directlink
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: 1979 mercury 115 hp no spark to any cylinders

Disconnect the orange wires at each of the switch boxes and recheck for spark. If you now have spark there is a problem with the kill circuit. You don't need the idle stabalizer.
 

asjeep

Recruit
Joined
May 13, 2011
Messages
5
Re: 1979 mercury 115 hp no spark to any cylinders

We have spark but only to odd cylinders 1,3, 5 .... i failed to check the mercury switch properly.... or perhaps guy had it upside down... either wait it is now disconnected...


any ideas on the even cylinders?
 

1979checkmate

Petty Officer 1st Class
Joined
Jan 15, 2011
Messages
261
Re: 1979 mercury 115 hp no spark to any cylinders

sounds like a switchbox went on you. One box controlls spark to odds, the other evens. You can check by swapping the two and see if the no spark situation goes to the odd cylinders.
 

asjeep

Recruit
Joined
May 13, 2011
Messages
5
Re: 1979 mercury 115 hp no spark to any cylinders

looking at the diagram it should be the lower one... will swap and test....

question do they really have to be replace in pairs? or is this just a "best practice" trying not to Break Out Another Thousand :)

already need a new trim pump assembly, seats and carpeting....
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: 1979 mercury 115 hp no spark to any cylinders

Its best to replace in pairs due to the bia's circuit in switchboxes. Disconnect the stablizer and jumper wire between the switchboxes and retest as a bad bias in the s-box thats firing can cause the good s-box not to fire. Ditch the stablizer as it can damage the bia's circuit and cause motor to "melt down" plus damage s-boxs
 

asjeep

Recruit
Joined
May 13, 2011
Messages
5
Re: 1979 mercury 115 hp no spark to any cylinders

Found the issue..... was in the pics as it turned out.... the bottom switch had been mis wired by the previous owner.... red to blue, blue to red....... all 6 firing now.....
 
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