2019 F200 shutdown while runnung

First time forum user.
Yesterday I was underway when the port motor just shutdown. I have a 2003 Gulfstream with two 2019 Yamaha F200's with 70 hours on. New start switches and gauges were installed when repower was done in 2019. Batteries were 12.8V on the 2 banks. I tried to restart the motor, noticed the port gauge was off as well. Tilt was inoperable, although the independent tilt switch is working on starboard motor. I have 12V at starter. it appears that the fuses on the port motor look good, I am going to remove them/check them today. Trying to narrow down what is wrong, including possibly port key switch. The fact that the gauge is off (doesn't display anything) is stranger.


Any ideas would be appreciated.

Checked fuses at eng and found that the one labeled 'Main Switch' popped. I replaced it with the spare 20amp in eng and all works (gauge and motor). Still dont know why it popped but at least I can get the motor working. Off to get another spare.

Still need to figure out what caused the fuse to pop. Will start at connection at wiring harness at engine side and try to get through to the gauge and key set up.

Still having intermittent issues with the port engine, Main/PTT fuse. Mechanic says he found a loose connection, but I am skeptical. I will be running it this weekend. If the fuse blows, I may replace the fuse and try not changing the trim for a long time and see if the fuse doesn't blow. I am also doing a visisual of the connections between the engine to the keys as the dash to see if there is anything looking odd, corroded, etc that might be creating a short. These intermittent issues are a pain to troubleshoot.

Mechanic indicates it is a problem in the engine harness (a bad diode or something?). It is underwarranty but harness is backordered. I assume more to come. I am also going to replace the wire harnesses that go from the engines (twins) to the binnacle at the dash. May replace the binnacle as well. Both are 18 year old and sees salt spray. I'm thinking preventative measures. More to come.
Len

Slight update. It took a while to get the part, but it was installed and got my boat back yesterday. I will run it Sunday with my fingers crossed. In addition to the warranty harness replacement, I installed new (almost 20 year old) rigging harness (from helm to binnicle) and a new binnicle. I wanted to start out with fresh wiring and especially new connectors.

Had a good trip from to Catalina Sunday. A little frustration at the launch ramp. Port motor started right up, that's the one that has the problems. Starboard wouldn't start, not even turn over. After cussing on it, and that didn't fix it, I took truck/boat to back end of launch area. Worked on it for almost 3 hours before I figured out one fo the two paraled batteries connections wasn't connected. My guess is that the mechanic had to take the battery set-up apart to get the new rigging harness and didn't but it back. Between that and me cleaning up all electrical connections, it was good to go. By then the wind/chop picked up so it was a good test. Had to adjuct friction of throttles on the water, which worked out okay as well. Hope the intermittent issue has been finally solved.