94 750 sc no spark

[stevenpuckett]

I have a 94 750 with an intermittent no spark problem. It will run fine for an hour then start missing and eventually die.it will usually take several days of sitting and will have spark and run. It has done this the last 2 times out.replaced plugs after the first time but I dont think they were the problem.the tips were brown and not very wet or fouled.
Is there a diagnostic flow chart for the ignition system? I am trying to avoid throwing parts at the problem.I am a big boat mechanic that just needs some specs to make a correct diagnoses
Thanks
steve