1986 80 hp merc

[Aaron Lariscy]

I just picked up a new boat last night with a 86 80hp on it. A quick check shows I have fire on cylinders 1&2 but not 3&4. Any suggestions on what direction to head with it from there. I'm going to comp test it this afternoon as well.

 

[CharlieB]

Re: 1986 80 hp merc

Swap trigger leads 1 & 2 for 3 & 4 to see if spark moves to 3 & 4, If yes then the trigger is bad.

If no then swap coils between 1 & 3 and 2 & 4 to see if it is either the coils or the switchbox.

Ideally, you would confirm any diagnosis by proper DVA testing per the CDIElectronics Ignition Troubleshooting Guide as there is NO RETURN on electrical parts.

However, if spark changes the cyl pair when you swap the triggers, that a pretty sure indication the trigger is at fault.

Just remember DO NOT try to start the motor until all triggers are back to their original connection positions as the timing will be radically wrong and possibly cause serious damage if the wrong cyl tries to fire way out of time.

 

[Aaron Lariscy]

Re: 1986 80 hp merc

M

Swap trigger leads 1 & 2 for 3 & 4 to see if spark moves to 3 & 4, If yes then the trigger is bad.

If no then swap coils between 1 & 3 and 2 & 4 to see if it is either the coils or the switchbox.

Ideally, you would confirm any diagnosis by proper DVA testing per the CDIElectronics Ignition Troubleshooting Guide as there is NO RETURN on electrical parts.

However, if spark changes the cyl pair when you swap the triggers, that a pretty sure indication the trigger is at fault.

Just remember DO NOT try to start the motor until all triggers are back to their original connection positions as the timing will be radically wrong and possibly cause serious damage if the wrong cyl tries to fire way out of time.

Excellent advice I have only one question for you, is there anywhere online I can find a wiring schematic or do I need to buy a repair manual or...

 

[Aaron Lariscy]

Re: 1986 80 hp merc

Ok update I checked compression and its a good 120 across all cylinders. Next I swapped the trigger wire of coil two to coil three and the spark followed so then it's the trigger right. Well next thing I know I have very weak to no spark on one and two all of a sudden. Started poking around and found a completely rotten wire it runs from the switch pannel to up under the flywheel and is pink where it attaches to the switch. I am thinking this wire may actually run up to the trigger but then again I don't know much about this motor. What is the procedure for removing the flywheel?

And to complicate things further I can't read the serial number, the last four digits are 1007 and the model number is 1258f90.