2007 F 250 4 stroke catches on fire

[rmartin00]

Just had a scare. I went down to the dock October 7, to do some storm preparation ahead of MATTHEW . I lowered the boat outboard engine into the water. Started it up and let it run for about 15 minutes. Switched it off, removed the key and started to leave the boat. On the way by the stern I smelled an electrical fire. I thought it was the electrical post by the boat so I went to the marina office and informed the dock master. We both went back to where the boat was docked and smoke was coming out of the cowling of my engine. I turned the battery switch off and the smoke subsided. I took the cover off the motor but was unable to see anything burned.

I called the technician Saturday and told him what had happened and requested he look at the engine. He initially thought it was a short to the tilt and trim because that was the only thing which was powered when the switch was off.

I went down to the boat today and see the tech had removed a Regulator Rectifier which was laying in the bottom of the boat. It was definitely burned. It had juice coming out between the plates. My Question is. How does the Regulator Rectifier burn up with the ignition switch OFF? Any help or discussion would be appreciated.

[boscoe99]

The ignition switch does not affect the connections (battery cables and red R/R wires) between the rectifier/regulator and the battery(s). Only the battery switch(s) (if installed) does this. See diagram below.

The wires from the R/R are somewhat protected by a 60 amp fuse but if current below this value is flowing there can still be quite a build up of heat which can damage the R/R and the R/R output leads.

Appears that in the grand scheme of things you got lucky. I have seen a lot worse fire damage.

[rmartin00]

2007 F 250 4 stroke catches on fire

Thanks boscoe99. I was very lucky. I learned a valuable lesson. Turn off your battery switch when you leave the boat.

[rodbolt17]

not the first F250 I ever saw let the smoke out. typically you will now replace the main harness and the rectifier.
why they do it? no clue, but I have witnessed it first hand.