My outboard caught fire today

[kwaka]

Hi.

Launched my new (second-hand) boat today, which ended with an engine fire 10min into the test run. It's a 16' runabout with a 1993 Johnson 150hp Fastrike outboard.

Apparently the boat has seen very little use in the last 12 months, and it looked ok when i inspected it.

Before launching it, i ran the motor a couple minutes and noted that the telltail was passing a reasonable amount of water (straight and steady), which looked ok to me. So I decided it was ok to proceed with a run. I did notice that the tachometer was not working however, and put it down to a faulty gauge.

After a quick 3-5 minute run, the engine cut-out on me and smoke billowed out the cowl. I immediately turned the ignition off and used an extinguisher. It smelt like an electrical fire. Got a tow back by the Maritime.

I later checked the motor and noticed that the regulator was severely cooked, and it has spewed plastic over the surrounding harnesses. I noticed that the red wire leading from the regulator to the positive on the motor was totally burnt and cut in half.

Anybody know what could have caused this to happen?

The motor sounding sweet and didn't miss a beat while it was running.

I checked the underside of the regulator and it seemed to have just the usual traces of salt, and not really corroded.

Do regulators depend on water cooling from the underside (fins) and how would you know if there is water flow to it, if the telltale seems to be flowing ok?

I've contacted the seller and will try sort something out, but in the meantime I need some info to go with.

cheers.

[Hamish73]

regulators dont rely on watercooling.
The fact that the red wire is burnt out indicates that an external fault caused the meltdown, possibly a short in the wiring somewhere, as opposed to a fault with the regulator. In other words, replacing the regulator will probably result in a repeat performance, so I'd be doing some tests before going too much further.

[seatime]

maybe a professional opinion? a sparky or outboard mechanic may spot if some backyard amateur electrical wiring has been performed.

or post some photos, someone might spot the fault??

must have given you a fright, good work putting the fire out.
fire blankets are handy in those circumstances, they can be wrapped around the motor, and there's no mess to clean out afterwards.

cheers
Steve

[Burley_Boy]

Sounds like a dead short somewhere, usually caused by a wire shorting to the case somewhere, surprising that there was no fuse that went first, need to check the fusing situation and then trace the short the other side of the regulator, either it cooked all the way through or the regulator is shorting to earth.
good luck.

[kwaka]

I took some photos but need to upload them someplace first to link them (not sure where).

If anybody knows a good mechanic that works the St.George area(NSW) please let me know.

I don't really know what to look for when it comes to electricals. I don't really understand how an external short melts down a regulator?

What i do know however is that I'm glad I took an extinguisher, and there's nothing like an unwanted BBQ to get the adrenaline pumping.

I'll post some pics when I figure out how to.

Cheers.

[Poodroo]

Tachometers not working is normally a good indication of a short somewhere too. Would not surprise me once the wiring fault is found and replaced as well as the regulator and you will also have a working tacho as well.

Poodroo

[Hamish73]

try www.photobucket.com for hosting your pics, then just copy the link into your post

[Roughasguts]

Poodroo, makes sence.
Either a stuffed regulator which it probably is now! or prior to it a stuffed rectifier.
I have no idea what that motor uses.

Have you got a twin battery set up ? and charging both.
That could cause a melt down, trying to pump Max Amps that along with coroded wire terminals.

Have you checked the engine main fuse, thinking that should have blown first.
But maybe not as the battery would take all those big Amps out, anyway see what Amp fuse is in there it may be way to big.

[newchum]

kwaka, mate you say the red wire from the reg was burnt and cut in half. it's possible that where the wire is parted is where it has maybe rubbed through and shorted to the motor case. causeing the reg to hemerage. don't look for a fuse in the red wire there is none. before replaceing the reg get someone to check the the rest of the wireing it may have suffer some heat damage

[kwaka]

Here are the pics:

[FNQCairns]

This is real typical of outboards, the rectifier dies takes the regulator with it then the charge coil under theflywheel keeps pumping the amps result is a fire, guaranteed the tacho was not working, if your tacho stops there is a good chance a call to be towed is in order if you cannot diagnose on the spot or atthe very least a slow trip home to keep the amps down.
Kwacka the coil under the flywheel is shot also I suspect, try in the USA for sierra parts (better than original) and a damn side cheaper with freight of just a week sometimes, suspect in Oz your bill could be $1000 just for the bits that died.

[newchum]

This is real typical of outboards, the rectifier dies takes the regulator with it then the charge coil under theflywheel keeps pumping the amps result is a fire,.

fnq, not sure that what you are saying can happen, as the coils under the flywheel (which has been removed in the pics) generates a.c. current and once the rectifier open circuits there is no d.c. output from the reg and the red wire looks like it has taken a lot of current , looking at the melted bit on the end of the wire coming from the started pos. i think there may be a burn mark on the motor where it made contact. the coils under the flywheel would be melted as well if the fault got its power from them. my guess is the fault burnt the reg out and then got its power from the battery.

[kwaka]

More info:
-I only have one battery.
-I didn't remove any coils, just the top cover and the regulator for the photos. There are ignition coils (large coil pack) mounted on the back of the motor.
-The fuse didn't blow.
From what I can see, the molten plastic from the regulator damaged some of the wiring harness beneath it, and that red wire from the regulator to positive terminal lost all of it's shielding and severed.
Cheers.

[finga]

Have you got a picture looking straight into the battery feed stud on the start solenoid??
I don't think the burnt wire goes to the solenoid terminal in the picture.
Is the solenoid terminal in the picture go to the battery or to the starter??
Newchum could quite well be on the money and it was just a jesus box blowing. Why Jesus box??? 'Cause when that goes you start praying.
Anyways the spewed plastic is just the pichy/resin type stuff out of the regulator/rectifier and not to much to worry about but definitely get the rest of the wiring checked.
A blown rectifier is just one of many reasons why a tacho may not work
Bit of a bad start to Ausfish matey. I hope things only get better and love to hear some good reports from you soon
Cheers Scott

[kwaka]

Yes the red wire goes to the starter solenoid post.
I don't think it has a rectifier? Here's a diagram of my motor >> http://www.crowleymarine.com/brp_par...rams/38636.cfm

Thanks for all the responses and yeah, i do hope things work out and I get more than a couple minutes of joy from my investment.

Cheers.