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Mercury 30 HP, manufactured around 2001(guess) not firing

T

thommm

New member
Hello,

My uncle brought in a Mercury 30 HP from around 2001 I guessed by comparing it to photo's on the internet. It looks very good, and has been maintanted properly as far as he knows. It is currently not firing on any cilinders. I am studying electronics engineering so I have been working on it for a couple of days probing around with my scope, and doing research.
The results so far:
  • If the power lines (green/white, white/green) are disconnected (or one of them), I get a near perfect sine-wave at around 360V peak-peak.
  • If the power lines are connected, but the ignition coils are disconnected, I get half a sine; bottom side is as expected, but the top is capped at 20V peak(I don't have screenshot, but take the picture below, and add the bottom half of a sine on the places where it is 0V.
  • If the power lines are connected, and the ignitions coils (1 is enough) are connected too, I get this, it's around 20V peak-peak(Settings are on the side and top):
hrK7n2f.png


  • I get no signals on the lines going to the coils, one coil has 4 wires, a black one, and 3 other cables I measured with a diode meter and an ohm meter, one of the lines has 40 ohm referenced to ground, the other ones are a strange diode configuration (I guess that explains the capping of the bottom side of the sine on the power lines).
  • My trigger line is showing a nice sine-wave of about 10V peak-peak if I remember correctly, I can remeasure them if that helps.


I am quite sure the power box thing is broken, but it is quite expensive, and I don't really have budget unless it is really necessary. If it's broken, it's broken and I will buy a new one, but I don't want to buy one and find out later that I missed something.

If I can measure anything else, or need to take pictures, please just ask.

Thanks in advance,

Thom Kouwen

P.S. I am studying electronics engineering, and am willing to learn, so get as technical as possible please :)
 
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http://www.maxrules.com/CDITSHOOTING.html this is the common method of ignition trouble shooting with resistance and voltage checks..you will need a peak reading voltmeter(dva) or an adapter for your multimeter...a scope is a good tool but most of the reference material we use is with dva meter readings and resistance...an inductive timing light is also handy... a scope would be interesting to use but there is not a practical need for it on an outboard ignition system....getting a scope out and getting into deep design theory is a time eater that the tech's dont need..i admit you could see an intermittent failure such as a coil breaking down or firing into an open intermittent or borderline load line with it but its just not day to day practical...i used a scope for 40 years and know where you are coming from though..interesting...
 
This is a twin cylinder 2 stroke? or a 4 stroke?? - having trouble figuring exactly what you have if you have the year correct.

Just trying to figure what "power box thing" you are referring to.

The twin 2S 30's had CDM ignitions, so mini switch box built in with the coil - not the typical Merc "switchbox", and the 4S had a computer (ECM).
 
galamb said:
This is a twin cylinder 2 stroke? or a 4 stroke?? - having trouble figuring exactly what you have if you have the year correct.

Just trying to figure what "power box thing" you are referring to.

The twin 2S 30's had CDM ignitions, so mini switch box built in with the coil - not the typical Merc "switchbox", and the 4S had a computer (ECM).
Click to expand...

Sorry for my very late reaction, I have been very busy with school due to a member of a project dropping out, and me having to do double work. It's a 2 cylinder from 1997 according to an "expert".

I finally managed to free some time for the outboard. I got it running, it had:
- Two broken magnets, at first glance they looked fine, but when I investigated further, they where dislocated
- A fault in the stop-circuit, missed this, I hadn't always disconnected the stop-circuit when I was testing, my bad.
- One broken ignition coil, not a ohmic short, but a diode reading, no clue why.

So now it's running, but the pisser isn't, well, pissing. Normally I would just immediately replace the impeller, but it is puffing air. So I'm kind of doubting if it's the impeller, is it normal in case of a broken impeller that it is puffing air?


Thom
 
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