So here we were, putting back to the harbor after several hours of trouble free motoring on a calm day on Penobscot Bay, Maine. As I was idling back to maneuver to dock, the motor quit abruptly. I though I might of just run out of gas. Then I noticed a burning smell from the engine. I immediatly cut off the battery switch, fuel valve and grabbed my handy fire extinguisher. As I popped off the cowling, as expected, a flame jumped up from directly under the front center of the engine. I quickly squirted it out. Luckily a fellow fisherman was near and towed me to the trailor. Upon later inspection, it appeared the Regulator/ Rectifier has burnt and melted partially taking the engine control (ECU) unit out in the fire along with some melted plastic of the intake cover and some other stuff in the area.
Here is why I want to hear from you experts out there: I can just replace the damaged parts, but I need to know WHY IT HAPPENED and how can I prevent it from happening agan? Has anybody heard of this happening? This boat goes into pretty remote places offshore and a fire would be the end of those on board if they weren't as lucky as I was to be in the harbor. How could the short that caused this not be fused? What other components are in the circut, up or down stream from this that could cause this. How should I check it out after I put the new parts in. and will somebody please kick me if I ever think about buying a used motor over the internet from one of those fasr talking outfits in Florida with no factory trained mechanics and ignore you if you aren't sending them a fistful of hard earned cash!
George

I would recommend you take it to a Yamaha dealer before doing any repairs and let them completely check over for cause and damage.

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Boats.net
Yamaha Outboard Parts

Thanks for the quick response. I initially took that advice and tried to bring it to a local Yamaha dealer. They were understandably reluctant to even discuss looking at it since they said they were too busy to deal with a motor that was not purchased from them. Then the service manager said he never heard of this occurance and could change the parts but could not say why it happened or certify that it could not happen again. Hence my frustration and decision to be more involved. I do mechanical work for a living on pretty sophisticated equipment, but have limited outboard motor specific experience. Past experience and reputation of this "only show in town" dealer is the motovation see what other opinions I can find out there.

George,
I understand your frustration - what the heck difference does it make to the local dealer where it was bought? It's out of warranty - they will be able to bill the customer for the work? I don't understand it .
Here's what I would do:
First, get in touch with the factory - get online and try to email them. Try to find out who the rep is for your region. They should be concerned about what kind of service their dealers are giving the customer - and they should be concerned about one of their motors catching on fire, even though it is very rare.
Secondly, I would get myself a Yamaha shop manual for my model outboard and check out the wiring diagrams. Look at which fused circuit provides power to the rectifier/regulator (if that's where you think the short occured). Pull the fuse, if it is still there, and try to determine why it did not blow. All of the circuits, except for power to the starter relay, should be fused. And,
really, I wish Yamaha would fuse it also. Maybe, that's where a short occured, if so, then it's like several hundred amps of current feeding a dead short, and either the short burns open quickly, or there is going to be ignition of adjacent materials.
From what I have read on this and other forums, Yamaha's four strokes are very reliable - what you have experienced is very rare, and I don't blame you for wanting to find out the cause. Let us know how you come out.
Good luck [img]smile.gif[/img] ,
Ken K

old school problem, I would look at the battery cable connections were they tight? at the battery. recifiers burn if there is no where for the charge to go to, and I have never seen a loose connection in my 25 yrs. in the service bus. haha or the other one or many carbs are flooding and bam fire never seen that either.

You can call Yamaha at 866-894-1626.

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Boats.net
Yamaha Outboard Parts

To all of you who replied, thank you so much. This website is an awsome forum. Reading through the other topics, I feel the responders really know what they are talking about. I have the shop manual and will order the parts (where's a good place to do that?) and reply again when I found the cause.
George

George,
The best place to buy parts is from the sponsor of this forum - boats.net. Good service and great prices. Check out their online catalog above [img]smile.gif[/img] ,
Ken K

I don't know whether or not it applies to you but my F225 had a Technical service bulletin for the Rect/Reg that was addressed by the dealer under warranty. It's worth checking into.