I have a 1995 Crownline 225BR with a carbureted 350 Mag engine, Thunderbolt V ignition with knock sensor, and an Alpha 1 Gen II drive. I have an occasional situation where the engine will act like the key has been shut off for a split second and then immediately return to running fine. This occurs when cruising at speed. I rebuilt the engine, carburetor, replaced the fuel pump, and replaced the plugs, rotor, cap, and wires two years ago and it ran fine for the first year. Then this momentary cutout started last summer and would happen once or twice during an outing. This summer the cutout has become more frequent along with a hard start condition when both hot and cold. Yesterday I did some electrical testing just to check and make sure there wasn't a voltage problem contributing to the cutout. I have two GP 27 batteries with a dual battery switch. Last summer I replaced all of the battery cables with 3/0 welding cable as I got that free from a friend. I started by checking battery voltage and it was 12.65V. While cranking the voltage dropped to 10.2V. This was confirmed at the key switch and at the coil. I thought maybe the starter was bad as it sounds slow to crank. I checked the amp draw and it was 172A while cranking. As soon as the the alternator starts charging there is 14.2 volts at the ignition switch and the coil. With the batteries still sitting at 13+V shortly after shutdown the engine will fire immediately. If I turn the blower and radio on and let them run for 10 min. the battery voltage would drop to 12.3 and the voltage while cranking drops to 9.8-10 volts as measured at the batteries and the engine struggles to start and then idles really low until I bump the throttle and the alternator kicks in then everythings runs fine. I thought that maybe the coil was bad so I checked it and found resistance on the primary to be 1.2ohms, secondary at 10.3K ohms, and a little oil on the outside of the coil. I am assuming that the coil is bad and contributing to the hard start with low voltage. Any other ideas as to what is causing the momentary cutout. Usually coils will cause a loss of power in the upper rpm range as they breakdown but I have never heard of one causing the momentary cutout. Any help is appreciated.
