Help. Engine stopped with a nasty smell!

[alystra]

Merc 90 4str year 2000. Carbs. (It's the Yamaha block)

Bowling down the Sound of Jura, I was, when suddenly it was silent. Kill switch I thought, but it was connected. Plenty of fuel. Turned the key, absolutely dead. No instrument movement, the rev counter still stuck at 3600, my cruising speed. A foul smell of burnt insulation (like when a hand held tool burns out its motor) came from the air intake. I reckoned this was pretty terminal. What I did next is another story.

Later I had a look. Nothing really obvious, but the smell was still there, a bit around the flywheel and more around the ECU and rectifier?? on the front of the engine. . I also recalled that smell last time out, but so faint I wasn't sure if it was real.

In view of a recent thread on battery isolating switches, I'm thinking there's a problem with that or the main cabling from battery to engine. Guessing that there was a break in continuity or high resistance which has burnt something out in the charging system. Could this be true?

Anyone with experience of these engines got any thoughts as to where I should look first? (apart from the battery isolator). Charging coils? Rectifier thingy? ECU? Somewhere else?

The absolute deadness is symtomatic of blown fuses according to the manual. I need to tilt the engine up. Is there a way to do that directly by connecting another battery to the tilt relay terminals? Would it be safe to replace any blown fuses provided I don't start the engine?

Any good guidance appreciated.

[9D280]

Alystra,

Could you not tilt up manually using the release screw probably located thro' a hole in one of your clamp brackets?

I'm not fully clued up about these partcular machines, but there's a load of "high level" tests you could do which will work on any outboard:

Burning plastic smells doesn't sound like a fuse. I guess if it's ECU powered a dealer should be able to plug in a laptop & see what it thinks has died? Problem if you've burnt a charging coil out is that you'll need to remove the flywheel to get at it, however if you disconnect the cables & park an ohmmeter across them, you'll find out quick enough if the coils are open or short circuit.

Is your tacho a "traditional" one hanging off the coil side of the rectifier (the wires you disconnected above), or is it driven from the ECU? If your ECU is firing out a 3600 rpm signal when the engine is clearly not turning, coupled with the smell eminating from there you may have fried it? Does the tach drop to zero when you power off (batt switch), and after off- on does it go back to 3600?

I'd suggest poke the charge coils with an ohhmmeter (disconnect them first) then the battery cables at the engine with an accurate voltmeter. Then disconnect the tacho signal wire & try powering up - does the tacho show 3600 in all combination of power / signal wire - that might narrow it down - if it only shows 3600 powered up with the signal wire connected, my money would be on the ECU..... If it does it with power only, something weird is going on in the tacho. If it still shows 3.6K with the power off, your tach is likely mechanically gubbed!


Hope this helps, let us know what you find.

[jambo]

Tony sorry to hear of your trouble hope you got home without to much hassle!?
Eddie Crossan at Balloch is your nearest mercury man I have always found him very helpful over the phone, worth a try.
Cheers hope you get fixed up soon. I am heading up for a few days on Sun can wait for my three week spell end July/Aug.
Hope to see you on the water soon take care,
J

[Polwart]

Hopefully it turns out to be something easy enough to fix cheaply/quickly, as the weather up there must be perfect right now.

Originally Posted by alystra

I reckoned this was pretty terminal. What I did next is another story.

I'm looking forward to this... ...it will be thoroughly disappointing if you started the aux first time, made good speed to a safe haven and retired with a few beers... ...so make sure you build some drama into it!

[jambo]

I'm looking forward to this... ...it will be thoroughly disappointing if you started the aux first time, made good speed to a safe haven and retired with a few beers... ...so make sure you build some drama into it! [/QUOTE]

Me too Tony come on spill the beans!!
J

[alystra]

Originally Posted by 9D280

Alystra,

Could you not tilt up manually using the release screw probably located thro' a hole in one of your clamp brackets?

I'm not fully clued up about these partcular machines, but there's a load of "high level" tests you could do which will work on any outboard:

Burning plastic smells doesn't sound like a fuse. I guess if it's ECU powered a dealer should be able to plug in a laptop & see what it thinks has died? Problem if you've burnt a charging coil out is that you'll need to remove the flywheel to get at it, however if you disconnect the cables & park an ohmmeter across them, you'll find out quick enough if the coils are open or short circuit.

Is your tacho a "traditional" one hanging off the coil side of the rectifier (the wires you disconnected above), or is it driven from the ECU? If your ECU is firing out a 3600 rpm signal when the engine is clearly not turning, coupled with the smell eminating from there you may have fried it? Does the tach drop to zero when you power off (batt switch), and after off- on does it go back to 3600?

I'd suggest poke the charge coils with an ohhmmeter (disconnect them first) then the battery cables at the engine with an accurate voltmeter. Then disconnect the tacho signal wire & try powering up - does the tacho show 3600 in all combination of power / signal wire - that might narrow it down - if it only shows 3600 powered up with the signal wire connected, my money would be on the ECU..... If it does it with power only, something weird is going on in the tacho. If it still shows 3.6K with the power off, your tach is likely mechanically gubbed!


Hope this helps, let us know what you find.

Many thanks for the thoughts,9D280. Just had a very good look after a few hours reading the manual. All the wiring and connections seem in excellent condition. There are no joins in the main battery cables from the console to the engine. Voltage at the engine ends is perfect.

Did a resistance test on the charging coils - perfect.
Tested connections from remote control to ECU. perfect.

The 30 amp fuse had blown. The 20 amp was ok. Either one failing creates the symptoms I have.

There was no point in testing the Rectifier/Regulator, as a poke around the the back of it revealed that it was toast.

Main concern is what made it fail. Age (9 years)? Bad connection? The only change to the system since last year is a new battery. Do rectifier/regulators just die sometimes?

More concerning is that a new rectifier is listed as POA . Whatever caused the problem, I need another one.

[Polwart]

Originally Posted by alystra

More concerning is that a new rectifier is listed as POA . Whatever caused the problem, I need another one.

are the o/board specific or is there a car motorbike equivalent somewhere for a price they are not too embarrassed to publish?

[eilean mor]

hope its not too time consuming or expensive - saw the boat with the engine cover off this afternoon as I was trailering in, but couldnt see you or I'd have stopped by, - if you need any 'bits' picked up, I'm in and out of Glasgow/ Edinburgh over the next week,

and please share about the trip home, as my aux is about the same size as yours, -


oh, and I saw the dolphins in oban bay when passing through there earlier this week at 2330, they came alongside as we cruised thro

[Jizm]

Originally Posted by Polwart

are the o/board specific or is there a car motorbike equivalent somewhere for a price they are not too embarrassed to publish?

Quite likely, I may be able to help if it's bike based...

[Marinautic]

Originally Posted by alystra

More concerning is that a new rectifier is listed as POA . Whatever caused the problem, I need another one.

As a mercury part it's listed as NLA, obsolete item!!