I have been having issues with the port engine on my 03' 32 Sunsation. When I had the engines out 6 years ago I went with a complete MSD Marine Ignition setup including box, distributor and coil. Fast forward to this year and I had what I thought was battery issues. After a full charge in the Spring and the boat sitting for 4 - 5 weeks and battery switches off I went to the launch and found that the Port battery was dead. After using a jumper pack it started but just as I removed the battery pack it died like the key was turned off. I hooked the battery pack back up and restarted it and let it run for 2 minutes or so with the battery pack hooked up. Had no further problems for the rest of the weekend. Tried going out the next weekend and found the Port battery weak again after charging it. The engine would start and then die. With leaving a jumper pack hooked up for a few minutes it would continue running. We left the boat tied up and charger on for the evening and had no problems idling back to the launch the next day.

I decided to pull the batteries as they were going 4 years old and have them tested. The Port battery tested at 100 CCA's less than the Starboard battery, I decided to go ahead and get new batteries and install them. Started the port engine on the hose at home and no problems. Headed back to the lake for the weekend and had no issues Friday night or Saturday. Sunday morning the port engine started and then died after running for five or so minutes. Headed back to the dock to tie the boat up and after getting that done it restarted again. Died again after 5 minutes or so....in all of these instances it did not cough or sputter. We ended up testing the MSD coil and it was out of spec. We ended up replacing the coil and it seemed to be ok but I was not confident the problem was fixed however it ran that evening and following day.

This past weekend we headed to the launch and the same thing happened. Started the port engine and it died after running for 2 minutes. It restarted and again died after 2 minutes. After thinking more about this I have noticed that my Livorsi GPS Speedo that is wired to the Port Key switch has been going through the reset cycle when on plane. I had thought that it had something to do with the small battery in the satellite but now think it is losing power intermittently. I went ahead and replaced the key switch and tested the kill switch with an ohm meter. My plan is to head to the lake again and see if it happens again. If it does I will plan on seeing if when it dies if I can see a voltage drop on the purple wire on the key switch. I also made up a jumper wire to eliminate the kill switch if need be. I have checked all of the ground lugs on the back of the engine, cleaned the ground on the alternator and checked for loose connections everywhere. I know the MSD boxes are prone to failing however have always heard that when they fail they fail....no intermittent issues with them.

What other things should I try if what I have done does not correct the problem? Could the key switch have been shorting out causing the problem? Thanks in advance for your help and sorry for writing a book lol!

Swap msd boxes side to side mike

Sure as heck sounds like the port alternator.

This can be done but they are wired to the starter and a pain in the arse to get to. The ground is hooked to the ground stud on the back of the engine. I wonder if I could add a bullet plug or some other type of plug to where I could more quickly make the change moving forward for both the red power wire and ground? Any thoughts on this? I do have a new box though but just thought it was not the problem.

From what I gathered from your post is that you are actually using your boat. Congrats!

Thanks for the feedback! I typically run both battery switches on both. With that being the case do you still think the alternator could be the issue?

Does that connect both charging systems together ?

Edited above, brain and fingers did two different things.

Are charging systems tied together when you have both switches that way ?

Guess I am not sure how to answer the question. The switches are tied to one another....there is a cable that runs between both.They have the off, both, 1 and 2 selections on them.

I had a similar issue years ago when I had MSD. The problem was in the weather pack connector. The big one with several wires going to it.

Did you do a "draw test" to see if you have anything drawing power from the battery, when the key switch is "off"?