Motor just died

[Eastbayboy]

Ausnoelm: According to the wiring diagram the negative battery terminal goes to the motor and then a ground wire goes out the main connector between the boat and motor.

Panasonic: No don't know anyone I can trade with, unfortunitly.

Robolt17: Yes, it does have a red stator.
I checked the pulser coil and charging coil at the CDI connector while cranking and both signals were there although both were higher than the manual by about 20%. I also check the kill switch at the CDI and it was working ok.

99yam40: I built a peak detector circuit to check voltages. The pulser and charging coils both read high (about 20%)and the CDI output to the coil read way low. Can't really use the manual for voltages but it does say 2 signals are there and one is barely there.

[panasonic]

Here is a DVA I got on Amazon for $75.00 Canadian to check my CDI. It worked very good.

[99yam40]

Ausnoelm: According to the wiring diagram the negative battery terminal goes to the motor and then a ground wire goes out the main connector between the boat and motor.

Panasonic: No don't know anyone I can trade with, unfortunately.

Robolt17: Yes, it does have a red stator.
I checked the pulser coil and charging coil at the CDI connector while cranking and both signals were there although both were higher than the manual by about 20%. I also check the kill switch at the CDI and it was working ok.

99yam40: I built a peak detector circuit to check voltages. The pulser and charging coils both read high (about 20%)and the CDI output to the coil read way low. Can't really use the manual for voltages but it does say 2 signals are there and one is barely there.

well if there is good going in and not coming out and the kill circuit is not grounding the output, then you are left with a bad CDI as far as I can tell.

By the way the manual gives minimum specs, so over is still good

[Eastbayboy]

Something I just noticied on the wiring diagram (Homer Simpson DUH) which could be causing my problem. There are four wires going from the CDI to the three ignition coils. One wire (orange) is common to all three coils. The other three wires (black and other colors) go back to the CDI. I assume the orange wire the the hot wire and the other three are grounded when needed. I have alway checked the signal from the CDI to the ignition coils with the other two coils connectoed. Which if one is coil bad would always give me a bad reading.

I will check the signal form the CDI to the ignition coil again tomorrow, but with the other two coils diconnected. If I have a bad coil I should have two good signals and one bad. I did ohm the coils out and they were good.

Eastbayboy

[Eastbayboy]

COMPLETELY BAFFLED???

Well I bought a new Yamaha CDI from iboats.com and it does the exactly the same thing the old CDI does. Everthing looks good except the signal going to the ignition coils is 35VDC (120VDC spec).

I hate to admit defeat but I can't think of what to check now. I am almost to the point of taking it to the Yamaha dealer???????

Eastbayboy

[99yam40]

is that connected to coil (loaded)?

[Eastbayboy]

99yam40: Unloaded I measured 35VDC. Loaded I measured 0.5 VDC.

Taking the unloaded measurement it took about 3-4 seconds to get to 35VDC and then it held there. My guess is that it should hit the voltage immediately.

Also, there is a diode between the ignitions coils hot wire (orange wire which goes back to the CDI) and ground. When I disconnect the coils and the diode then I measure 52VDC between the coil hot wire and ground.

Completely baffled???

[panasonic]

You got a new CDI so you are certain that works. You are not getting the proper outputs, SO you can't be getting the proper inputs to the CDI..

The stator is a common failure item on this particular engine as per Rodbolts previous comments. Maybe go back and check the outputs from the stator again.

[99yam40]

If there is something draining some of the voltage or the cap is bad it will not send on the complete voltage it gets in.
just speculating here as he said incoming was good.

something is causing 2 different CDIs to do the same thing.
why not disconnect the kill circuit at the CDI and then measure the voltage again just to prover there is not a problem with that

[exeter27]

You've really done a nice job covering all the bases - so it's hard to say where to next venture. I had a motorcycle that was giving me fits - and it turned out to be a bad pulser unit. It was years ago, so I don't remember details (my wife suggests I don't remember many things . The pulser is what gives the signal to produce the spark. Without that, you never get a spark. You said you checked the pulser circuits - was it strictly resistance? I don't know if there's a way to check that voltage is produced - and at the right time. And more years ago (say early 90s) I had a Honda Prelude that had an igniter (I think same as pulser) that would go bad as it heated up. I "borrowed" the same unit from my wife's Accord to verify - and yup that was it. That only showed up when car warmed up.

So, if you can get to a junk yard (or if you have a gracious friend), borrow the pulser and see if that helps. My only other hunch would be an bad ground somewhere...all items can check out fine, but without a common ground, they don't work together!

[exeter27]

Sorry, after re-reading the entire post, I see that you verified the pulser - so you can dis-regard that part of the post. Ground is still always an issue, but it doesn't align with a sudden and non-intermittent no-spark situation. But, a poor ground could explain some of your incorrect readings. Have you cleaned all ground connections thoroughly? No doubt once you figure this out, it will be a quick/easy fix.

[rodbolt17]

that system uses a single pulser coil to create a timed spark.
it uses a single charge coil to charge the capacitors in the CDI.
the pulser fires the SCR's that allow the cap to discharge into the coil primary.
it is a dirt simple system.
however the CDI does not amplify the charge coil voltage to it.
that is why systematic testing speeds up the process and you don't own so many spare parts.

[rodbolt17]

that engine was designed by mercury.
the same year carbed 40 merc service manual typically has better explained systems.

[Eastbayboy]

Went back through the ignition system again. Everything looked the same as the first time through with the following exception. The first and second time through I measured the charging coil voltage unloaded at 290VDC, spec 200VDC. I never measure charging coil voltage loaded the first time. This time I did and measured 52VDC, spec 190VDC.

I also went through all the wiring for continuity and checked my grounds and all looked good.

Well now things seem to be pointing to the stator. Any other thoughts would be appreciated before I buy another spare part.

Thanks for the input!!!
Eastbayboy

[exeter27]

If I recall correctly, Rodbolt mentioned stator earlier in the posts. If he's wrong - well I've not yet seen it!