Re: 1999 mercury 125 not firing on 2 cylinders
Look at the ignition module, there is a row of terminals across the top, these are from the stator and provide the voltage.
There is also a row straight down the center, every other wire is a trigger, the others are green with trace lines of color leading to the coils.
The stator makes the voltage, the box stores it, the triggers tell the box which coil to sent it to and make a spark.
Remove the spark plugs and attach some for of 1/2 to 7/16 inch gap spark tester that you can watch for spark.
The green wires from the box should be 1 thru 4 going straight down the box, so should the triggers.
Switch the top two triggers with the bottom two and retest for spark, if the spark is now on the top two cyl and NO spark on the bottom, then order a new trigger assy. Note: All terminals on the box are marked with the color code, so you don't have to worry about putting it back together incorrectly, just put each color back where it belongs. For testing, leave all the greens alone, just switch the colored triggers an notice how the spark follows the trigger or stays with the same coil.
If spark remains on the bottom two cyl's then order a new switchbox.
If the stator failed you would have no spark anywhere or a weak spark at high speed, these are not you current problem.
