Mercruiser 5.7 EFI, mfg. 2001, Alpha One outdrive, 2002 Monterey Montura 218, don't have the serial #, can't read from cover. Engine ran fine last 2 times out, after having work done on the alpha outdrive (hit stump, broken gimbal ring). I replaced a stereo amplifier since then. Last Sun. the engine just turned over and over but wouldn't fire. How many switches, and fuses are there to be checked? Just need some ideas and what to look for that may cut the spark so the engine won't turn over. Shift interrupt switch? Run switch has been on. Checked all fuses under helm. Don't know where to proceed from here. Any suggestions would be appreciated, thanks. (I'm 95% its a spark issue not fuel, no spark from coil.)