F80 lost all electrical power and was smoking

[Gurkenrat]

So here is the order the events happened today. Trying to figure out whats up with my motor. its a 2000, f80. Used it last sun and it ran fine, no issues. Went out today and battery was at 0 volts. Bought a new battery and installed it (yes the wires were hooked up correctly). Motor started first try and all seemed good. Then 30-45 seconds later, motor died. All the electrics in the boat are dead too. Turn the key to on an nothing has power. Battery is still showing 12.4Volts. When we pulled boat out of water, could smell burnt electricals. Took cap off and there was smoke trapped inside but the specific item could not be identified. I did a bit of searching and could not find a burnt wire. I wasnt able to locate the main fuze either but I am assuming it was toast.

So what could possible have drained my battery to zero while the boat sat for a 5 days? Then when the new battery was attached, start the motor and allow it to run for a but before dying and starting to smoke? Rectifier? There is still 12 volts at the solenoid but the key does nothing. it wont urn over and all the gauges are dead. I am assuming all of the power to the boat comes from the motor? None of the fuses in the boat itself are blown.

Thoughts? How can I test or isolate rectifier to see if its the problem?

[Gurkenrat]

Found this 30amp fuse and it was cooked. All others are good

[99yam40]

time to chase down what is shorting

[Gurkenrat]

Ok. So that 30amp fuse according to my manual is on the power trim and tilt relay. I did have one intermittent episode last time it was out where I tried to tilt it with the throttle and nothing happens. Then suddenly it worked again. So it’s something in the PTT system. Question is could the short be outside of the motor and cause the fuse to pop? Remember, there was smoke under the cowl when we lifted it.

[panasonic]

Follow your nose....if there was smoke you will smell what is burned up! Find that trim relay and smell it. Put a lower amperage fuse in..say a 15 or 20 amp and see if it blows immediately or when you hit the trim button...

[Gurkenrat]

There is definitely a smell around that relay. And I was thinking about replacing the fuse and trying all the trims to see if one button or one direction blows the fuse. I can say this morning I moved the motor with the motor switch to remove the transom saver. Wasn’t aware of any issue. But then we launched boat, it started fine and the motor lowered using the throttle trim button. Now, I can’t state that there wasn’t something going on under the hood after starting or lowering the motor. But within 30-45 seconds, the motor died and all electrical went with it. I MAY have tried to raise the motor a touch just before it stopped but can’t remember for sure. Going to pull it apart this weekend and look at the relays closely and the rectifier etc…

[99yam40]

the T&T pulls a lot more that 30 amps on most motors I have known about.
now maybe the coils, wire to them, and switches would be on that fuse, but not the T&T motor power itself

[Gurkenrat]

The part I dont understand is why it drained my battery over the last few days. Everything seemed fin last sun when I had it out. This morning the battery was dead. Then when I replaced the battery, nothing was smoking or making noise. It wasnt until I started it and began normal things that the fuse popped and the smell of burnt wire appeared. If it was a true short that drained the battery, wouldnt it havr popped the fuse before this?

[99yam40]

if it was not a dead short and was just pulling close to 30 amps the fuse would hold for some time

[zenoahphobic]

Just 1 amp drain over 3 days will flatten a battery. So you might have a small leak not necessarily related to the 30 amp fuse blowing.
My guess is your trim motor might be on its way out and has strained the relay and the contacts stick. That or the manual switches one is shorting by some means, could just be water (sea water conducts electricity well). Just where you might look.

[Gurkenrat]

I am in freshwater but oddly enough, the transom switch was getting a small amount of spray from the repositioning of the transducer when I had the transom done. I went over everything today and could not find a burnt out wire under the cowl. None of the components look damaged. I feel like I’m looking for a phantom. Ughhh. So no using the boat until I find something that isn’t exactly standing out.

[Gurkenrat]

So how do I go about diagnosing this? Do I have to tear all the flooring out and hand inspect every inch of wiring to find the slow leak? How can I test the PTT motor? If it’s not that, where do I start? Test all the relays?

[panasonic]

I am confused...was the smoke coming out from under the engine cowl or under the floor?

[Gurkenrat]

Under the cowl. But that’s also where the fuse is but I can’t see the fuse creating that much smoke. Unfortunately, all we saw was the trapped smoke as we pulled boat out of water before we could smell the burning. After a good inspection today I wasn’t able to find a burnt wire or anything obvious. The smoke from under the motor cap leads me to believe that’s where the problem is. Just need to find it. But not sure what in there could have drained the battery then caused the fuse to pop soon after motor was started

[Gurkenrat]

Back to what zenoaphobic mentioned, water. Could water cause if we’re to have penetrated the trailer switch? I did have a slight amount of spray from a transducer landing in that area but figured it’s outside all the time so what’s the difference? The other water source that I never considered is the motor now sits in a semi raised position on the transom saver. The back of the hood has that open slot. We had a wicked rainstorm last week. I doubt it’s something that simple but I’m curious if water penetrated from either of those spots, if it could be culprit. Either way, I guess I need to start testing stuff to find out what the issue is. Just not sure where to start. If the PTT motor is going and that is straining the relay, how can I determine that vs just a faulty relay?