I have a 1987 90 HP evinrude that is giving me problems ,here is the diagnosis. The motor is freshly rebuilt and compression is top notch , the motor starts fine but after about 30-45 seconds of running it will cough and sometimes its enough to kill the motor.It seems to me like some sort of ignition problem, here is what Ive done to troubleshoot the issue,
1) put new carb kits in it and tested VRO pump with new one = all is ok
2) tested and replaced timer base and flywheel= OK
3) tested and replaced stator=ok
4) The only thing I havent replaced is the powerpacks???
5) tested voltage regulator/rectifier= all is ok
6) checked all coil wires and coils= ok
7) All 4 cylinders have spark but it seems intermittent on both sides, a bit weaker on the starboard side
8) unhooked black yellow wire for kill switch =tested ok
Is it possible the guy who owned this before me burnt both powerpacks? It looks like he replaced the starboard pack .How do you test the packs with inexpensive tools, I have the DVA meter and a good multimeter.
Any help is greatly appreciated.