Yamaha 90A 2 Stroke (2010) - Intermittent No Spark - Can anyone help?!

[ausnoelm]

Loaded mean running, unloaded means unplugged. The three cylinder 90 Yamaha has a very unique ignition system, cylinders 1&3 spark is generated different to cylinder 2. If you have no spark on ALL cylinders, then it kind of changes the ****, please test spark on ALL cylinders and let us know what the result is.

[MarkScott18]

Loaded mean running, unloaded means unplugged. The three cylinder 90 Yamaha has a very unique ignition system, cylinders 1&3 spark is generated different to cylinder 2. If you have no spark on ALL cylinders, then it kind of changes the ****, please test spark on ALL cylinders and let us know what the result is.

Thanks, just to confirm, are you really saying that "unloaded" means connectors unplugged, and "loaded" means connected AND the engine running? Seems strange to me, but important that I know the exact meaning for tests to be relevant.

Forum censored one of your words, kind of changes the **** - changes the what? Test?

Can you please tell me how to 'test the spark on ALL cylinders'? I have spark plug lights fitted, so I alwas know if there is or isn't a spark. Do you want me to get voltages? If so, peak I assume? Which wires do I test from, it seems there are various ways to do this. Am I right in thinking it's the B/W wire to each ignition coil (with red probe) and the bolt head/earth of that ignition coil (with black probe)? If so, Do i do it with it connected or unplugged? (Obviously I can't test with engine running unless I have a spark, which is possible.

I really need to get serious and careful about my testing, especially in light of the prices of these damn parts!

Thanks

[99yam40]

since the charge coil Ohms read in spec when there is spark, and is way out of spec when it is not sparking
I would be looking for a bad connection or wire to the charge coil.
may take some doing to find, but you may be able to repair the connection/wire.

and yes you are correct, loaded is connected,
unloaded is unplugged.
I also thought his wording of running for loaded was strange

[MarkScott18]

Thank you so much. So to inspect wires to charge coil, I am guessing I need flywheel off? I may have to get a friend over with a puller as I don't have one. I will do some more tests today, including getting all peak voltages again (this time leaving plugs connected!!), just in case that adds anything confirmatory.
General electrics question - which is the most reliable test of a component, resistance, or peak voltage? Trying to work out why Yam book goes for peak voltages in the troubleshooting section, when that needs special equipment (DVA), whereas everyone has a meter that can test ohms! (I wouldn't be surprised if the true answer is "so you go buy Yam's multimeter/diagnostics tool"!!)
Thanks again, very much

[MarkScott18]

Update: I took more readings today. I decided to use Boscoe's picture posted earlier, I edited it to add my values alongside. I can't test most of these connectors when 'unloaded' (unplugged), so all readings taken while disconnected, except the 3 ignition coil readings which use bullets I can get my meter probes into while leaving connected, although I took readings disconnected as well (which made a big difference as shown below). Any thoughts very welcome! Thanks all.

[MarkScott18]

Please ignore this post, I can't delete it

[MarkScott18]

Accidental message - Deleted

[MarkScott18]

Anyone know how to delete your own messages on the boards?

[MarkScott18]

I would be looking for a bad connection or wire to the charge coil.
may take some doing to find, but you may be able to repair the connection/wire.

Just re-read some scribbled notes I made when first got the boat home after the break down. They seemed irrelevant before but may now be more relevant in light of your comment quoted above.

The notes read: "Crank position sensor - disconnected, Ali put meter probes in to test voltage when I turn key, but when I did it fired into life, having had no spark until then."

Later on I read on these boards (Boscoe I think) that this engine will run without the CPS connected at all, so I am not interested in whether the CPS was connected or not, BUT...

THE WIRE from the CPS connector runs up to the stator and alongside the wire to the Charge Coil. Maybe him knocking/moving the wires caused whatever was needed to get the charge coil functioning again. So maybe you're bang on re a fault in that wire to the charge coil.

I have a friend coming over in an hour or two with puller and copper hammer to remove flywheel for me. I will get a good light and make a good visual inspection of that wire. Just wondering if there is anything else I can do to check that wire? Someone mentioned you can push a needle into the wire (through insulation) as high as possible, and check for continuity over as much of the wire as possible. Is that worth a shot?

Thanks for any ideas

[MarkScott18]

Update with pics

Removed flywheel. Checked all earth points, seem good to me. Checked both visually and with meter/conductivity.

Stator - charge coil pick ups look a bit rusty to me, but my friend who was here has seen a lot more engines than me (I've seen, er, ONE!) and said that shouldn't cause any issues.

Removed the grey wrap around the three wires that go up to the charge coils. Visually inspected very carefully, look perfect. Then did conductivity test using a sewing needle at highest point I could get on the three coil wires (red, brown, blue), other end at connector. All three had conductivity. Checked resistance on all three, 0.1-0.4, which I think means the cables are good.

So sadly I can't see any reason why the wiring is bad causing the problem, which takes me back towards the damn charge coil or CDI. Spoke to a very knowledgeable guy today (30+ years as a spe******t not just in Yams but this particular engine). He was adamant that a failed coil (i.e charge coil) would not be intermittent, his opinion was that it's not even possible as it's a coiled wire. It either breaks or doesn't, shorts or doesn't, but can't be on and off. Not sure how right he is, but I am in no position to argue with someone that experienced, although I'd highly value an opinion from anyone here too on that point.

There are two things we did find today which I suppose could be related, but I don't think so. I will mention them anyway...

1. Yellow connector which I dug out of the wiring under the CDI - book suggests this is "ignition wire". Not sure if that can affect spark, but my friend noticed the bullet connector (metal inside part) was clearly yellowy orange, compared to the grey/silver colour of all others. He said it's corroded, but he didn't have his glasses with him so couldn't see very clearly! He suggested I clean it up anyway and I of course will. It wasn't 'rusty' per se. Just discloured, almost bronze. It looked like the same connector as all others, the greeny see-through waterproof bullets (yam factory I assume). If so, the difference in colour must mean something.

2. On the communal earth point on the CDI mounting plate, there are various black wires connector together under the bolt. One goes off to earth (head), one goes to thermo switch and so on. But we noticed there's a clump of 3 or 4 black earth wires together in one connector on the bolt, but one appears to have been CUT at some point. Its orange/corroded on the exposed metal, but it's a very clean cut. At first we thought "aha, another rusted off earth!" but on closer inspection it looks like someone at some point has cut it, and probably fitted a replacement. The last two pictures show this.

(Had to make two posts as max 4 images per post)

Thoughts welcome

Thanks

[MarkScott18]

Checked everything I can now. Final position is as follows:

Engine is sparking reliably. Connected fuel today and it ran for 10 minutes fine. Yet I got resistance readings across the charge coil of 22,000 ohms (versus 80 per the book), then after I ran the engine I got 74 ohms again.

I have no clue. I can't risk going out with kids on it (or without really!), but I can't determine the issue. I suppose if I was a millionaire I'd probably get a new stator (to replace charge coil), just because I could. But then if I was a millionaire I'd probably have a Boston Whaler and twin Evinrudes

Ho hum. Stuck. If anyone has any thoughts I'd love to hear them. If not, I guess it's just another pain in the ass life has thrown at me.

Thanks for the help I've received above

[99yam40]

move some wires around while it is running to see if it dies, is all I got.
you moved some around before and it started sparking.
if you move just one or two around at a time, you might be able to identify which is the problem if it dies/stops sparking