Yamaha 90A 2 Stroke - Anyone knowledgeable on coils?!

[markS]

Pulser Coil tests good (assuming a resistance test confirms it’s good if it’s in the range shown in book values.) I get 316 ohms and it should be 241-362.

Charge Coil contains 2 coils. One reads 205 ohms (book says 191-288) so that looks good. But the other one was reading 12-13 ohms when I checked a few days ago. I checked again yesterday and got a surprise when it read 6000-8000 ohms?! A bit later I noticed the engine began sparking again (have test lights fitted), so I quickly took resistance readings again to see how they compare when it’s sparking, i.e. when the fault is not present. I got a reading of 73 ohms on that same coil, WHEN sparking. Book says 64-96. Correct resistance when sparking, crazy readings when not sparking, so I get the feeling the charge coil needs replacing?

Sad part is... I have a feeling you can't BUY a damn charge coil! Have to buy whole stator assembly, apparently. If so, OUCH!

[markS]

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.

Thoughts welcome

Thanks

[spartacus]

Yamaha in their wisdom, in fact all the major manufacturers failed to use tinned wiring, so it’s not uncommon to find engines with wiring issues. On my 2006 Tohatsu I had an issue with my trim motor a few years ago. I checked the remote, the trim motor itself and the solenoids. I eventually traced the issue to a break in continuity in the wiring loom that runs in a conduit under the deck. The copper wire had oxidised, pretty much its entire length. It turns black, and a continuity test with a multimeter confirmed. I stripped in a new wire (tinned of course) and it was sorted.

Back to your issue. On the startor coil, I’d lightly rub the metal pick up points with fine 3M sandpaper to remove surface rust. Use a light oil to rub over the surface points afterwards and dry. Check the inside of the flywheel for any corrosion too.

I’d also pull all your bullet points to inspect, lightly sand and reconnect. Out of interest, can you can do further continuity checks on the wiring.

I hope you get it sorted. Any word on beamishken’s CDI to test?

[paintman]

Clean off the rust. It shouldn't be there & whilst it might not be the reason then it can't be helping.
Check & clean all connections.
Then see if it makes any difference.

When you used the sewing needle did you give the wires a good flexing & a gentle pull?
As mentioned earlier my own trigger wire problem wasn't visible as the break was inside the wire. Picked up with a multimeter as per the mercury manual tests. Wiggling would cause the reading to be fine, then not fine. A gentle pull of the wires resulted in slight stretching of the faulty one.
I did consider that increasing the rpm slightly which saw the problem resolve might be down to an increase in voltage enabling the wire to pass current but on reflection the trigger assembly moves as the throttle lever is opened & I'm now more inclined to think that that movement was pushing the wire ends into better contact.

I've had issues with internal corrosion on car wiring, last one being the fuel pump on my Range Rover. Found by using the sewing needle method just up the main loom from the pump connector. Just a couple of strands left, enough to show battery voltage on a digital multimeter but not to pass enough current to run the pump. I do wonder whether an analogue meter would have shown it up.

Notwithstanding the opinion of your expert you've said that you have a low reading on the coil when the engine won't work & a reading within spec when it decides to.
Once you've eliminated any wiring issue then it does point towards the coil.

I've recently replaced the main live battery to engine cable on my Mercury. Engine end looked fine, battery end had one of the two screws into the wire type connectors & needed frequent cleaning of corrosion. Replaced it with tinned wire (not cheap!) & proper crimped on ends.
Examination of the old one revealed a rigid section near the middle of the length which made a crunchy noise when flexed. Stripping the sheathing showed it too was corroded.
So any wire replacement I'd advocate using tinned wire!

[markS]

Originally Posted by spartacus

Yamaha in their wisdom, in fact all the major manufacturers failed to use tinned wiring, so it’s not uncommon to find engines with wiring issues. On my 2006 Tohatsu I had an issue with my trim motor a few years ago. I checked the remote, the trim motor itself and the solenoids. I eventually traced the issue to a break in continuity in the wiring loom that runs in a conduit under the deck. The copper wire had oxidised, pretty much its entire length. It turns black, and a continuity test with a multimeter confirmed. I stripped in a new wire (tinned of course) and it was sorted.

Back to your issue. On the startor coil, I’d lightly rub the metal pick up points with fine 3M sandpaper to remove surface rust. Use a light oil to rub over the surface points afterwards and dry. Check the inside of the flywheel for any corrosion too.

I’d also pull all your bullet points to inspect, lightly sand and reconnect. Out of interest, can you can do further continuity checks on the wiring.

I hope you get it sorted. Any word on beamishken’s CDI to test?

Thanks for this.

Funny, spoke to a friend last night and he said "may sound silly, but if you have to splurge on some guess buys, why not buy a new wiring loom/harness? It would be a load of work, but it would rule out all those wires". I don't fancy taking that on, but it's an idea at least.

When I got the boat I did a rewire with expensive tinned copper wire everywhere, BUT I didn't do the engine (too scared to touch that, it looked excellent though and still does). I basically wired up lights, horn, 12v outputs, put a new earth bar into gunnels etc. It was all soldered well and vaseline protected and looks like new. But of course that doesn't include engine wiring or even control box. That does all look good though, very good. NOt to say it can't be corroded inside of course, but the boat has been dry stored in a barn for past ten years, only seen light of day a handful of times this summer, until our scary breakdown a few days ago!

What interests me in your post is the stuff about testing wiring. I really am not sure I know how to do that. I have a digital Fluke meter, and I can do continuity tests of course. But I wasn't sure if hearing a good strong BEEP was enough of a test. When you said your wire had turned black and "a continuity test with a multimeter confirmed" - what exactly do you mean? Did you get no beep, no continuity at all? Since I have an intermittent fault, I am assuming I will get beeps sometimes, and I have a spark at the moment (last I checked). I can't check again now as the flywheel is off. Pain in the ass!!

I'm a bit hestitant about rubbing the pick up faces. I have wire wool, and some very fine sand paper. I see a smidgen of rust on all the faces all around the stator. I'd like to seem the shined up while I am at it, just worried I go and bugger the stator myself! As for inside of flywheel, not sure if any rust clean up needed there, couple of pics...




Bullets all look mint, except for that yellow one which book says is "ignition wire". Can that affect spark? Its bronze in colour which is different to all others, but looks like its the same factory Yam connector, so whilst it isn't flaking rusty or orange, the bronze discolouration might suggest it has indeed corrodod.

CDI - Yep, what a top guy. I have it here, not tested with it yet as the flywheel is off so I can't check the spark situation. Once i get it back together I will see, if i have no spark then that will be a good time to swap CDIs and see if I can influence the fault by changing that.

Thanks again

[markS]

Originally Posted by paintman

Clean off the rust. It shouldn't be there & whilst it might not be the reason then it can't be helping.
Check & clean all connections.
Then see if it makes any difference.

When you used the sewing needle did you give the wires a good flexing & a gentle pull?
As mentioned earlier my own trigger wire problem wasn't visible as the break was inside the wire. Picked up with a multimeter as per the mercury manual tests. Wiggling would cause the reading to be fine, then not fine. A gentle pull of the wires resulted in slight stretching of the faulty one.
I did consider that increasing the rpm slightly which saw the problem resolve might be down to an increase in voltage enabling the wire to pass current but on reflection the trigger assembly moves as the throttle lever is opened & I'm now more inclined to think that that movement was pushing the wire ends into better contact.

I've had issues with internal corrosion on car wiring, last one being the fuel pump on my Range Rover. Found by using the sewing needle method just up the main loom from the pump connector. Just a couple of strands left, enough to show battery voltage on a digital multimeter but not to pass enough current to run the pump. I do wonder whether an analogue meter would have shown it up.

Notwithstanding the opinion of your expert you've said that you have a low reading on the coil when the engine won't work & a reading within spec when it decides to.
Once you've eliminated any wiring issue then it does point towards the coil.

I've recently replaced the main live battery to engine cable on my Mercury. Engine end looked fine, battery end had one of the two screws into the wire type connectors & needed frequent cleaning of corrosion. Replaced it with tinned wire (not cheap!) & proper crimped on ends.
Examination of the old one revealed a rigid section near the middle of the length which made a crunchy noise when flexed. Stripping the sheathing showed it too was corroded.
So any wire replacement I'd advocate using tinned wire!

Great stuff thanks very much.
Where it gets tricky is the "see if it makes any difference" part! Without a flywheel on I can't crank it, so i need to put that on each time.

One question I do have - When testing coil wires the glue/resin which holds the wires around the charge coil broke a bit, loosening the wires. How should I fix that? I have hot melt glue and other glues (sticks like shit?!). Should I fix those back down with something? (pic below)

Yes, I got my son to flex and wiggle cables both while doing continuity check and reading the ohms (all under 0.5 ohms regardless of any any pinching and wiggling)

You mentioned your 'trigger wires' again, which I think means the white/black and red/black to the pulser coil. I ruled out that being faiulty a while back based on service manual checks of voltage and ohms. BUT, maybe I should check those anyway, as I havent and while i have flywheel off I may as well test those like i did for charge coil wires.

Part of my problem is lack of expertise with electrics. For instance, when I had readings of 12 ohms when sparking on ONE of the two charge coil tests (as per service manual), but then got 6000 to 8000ohms (when not sparking), I have believed 100% its the charge coil. I'm not sure if I SHOULD be doing that. Maybe I am being led by these ohms values too much? Either way, no harm in checking pulser coil wires for continuity and resistance while wiggling! Will do that later today thanks.

When you say "Picked up with a multimeter as per the mercury manual tests" - can you briefly explain what that test was? Just continuity beep? Or was it resistance?

Thanks again, really appreciate the help guys

[spartacus]

Originally Posted by markS

What interests me in your post is the stuff about testing wiring. I really am not sure I know how to do that. I have a digital Fluke meter, and I can do continuity tests of course. But I wasn't sure if hearing a good strong BEEP was enough of a test. When you said your wire had turned black and "a continuity test with a multimeter confirmed" - what exactly do you mean? Did you get no beep, no continuity at all? Since I have an intermittent fault, I am assuming I will get beeps sometimes, and I have a spark at the moment (last I checked). I can't check again now as the flywheel is off. Pain in the ass!!

I'm a bit hestitant about rubbing the pick up faces. I have wire wool, and some very fine sand paper. I see a smidgen of rust on all the faces all around the stator. I'd like to seem the shined up while I am at it, just worried I go and bugger the stator myself! As for inside of flywheel, not sure if any rust clean up needed there, couple of pics...

Normally if the wiring is oxidised, then chances are it will creep along the length. It turns black with corrosion, and loses continuity for the electrical signal, hence you may get intermittent fault.

The continuity test I use is just apply probes from multimeter (+ive) and (-ive) on opposite ends of the wire you're looking at and listen for continuity signal. You may have to adjust probes to check. Any break in the beep signal, then it's worth investigating further. If the other end of the wire is further away, say in the console, then you can use another wire with crocodile clip at the end. It's a bit Heath Robinson - but you get the idea.

On the surface rust, yes fine wire wool is fine. You're literally lightly sanding, nothing more. Even an emery board would work. Wipe clean with light oil to reduce chances of further corrosion.

Good news on CDI - once you get flywheel back on.

[paintman]

Stator and trigger on mine are separate items.
Not much use to you, but this is how mine should be.
Trigger: https://cdielectronics.co.uk/product...-6456-96455a11
Trigger on mine has 6 wires which are colour coded and the respective pairs are tested for resistance as set out in the factory workshop manual. 1100 to 1400 ohms. All 6 must be disconnected before any testing.
Two pairs were absolutely fine showing 1200 & 1218 on the meter & the last pair (isn't it always the case it's the last thing!) read 0.
Wiggling the wire suddenly gave a reading of 1200.
Continued wiggling made & broke the connection.
Replacement from the place in the above link who were excellent, 24 hour delivery.

You will need to put the rotor back on to test after cleaning, there's no other way you can check run the engine.
Bought one of the copies of the proper Mercury tool for removing the rotor on mine, under £20 IIRC but I learnt a long time ago that sometimes it's best to get the right tool to avoid breaking stuff & it also serves as the engine lifting tool should I ever want to take the engine off complete or the powerhead.

Don't know about the glue.
Perhaps you'd be better off with an epoxy as I'm not sure what sort of heat there is which might melt hotglue?

Must admit I'm not fully Ofay with electronickery devices but fortunately the manual is written in simple language that even I could (eventually!) follow.

[markS]

Originally Posted by paintman

Stator and trigger on mine are separate items.
Not much use to you, but this is how mine should be.
Trigger: https://cdielectronics.co.uk/product...-6456-96455a11
Trigger on mine has 6 wires which are colour coded and the respective pairs are tested for resistance as set out in the factory workshop manual. 1100 to 1400 ohms. All 6 must be disconnected before any testing.
Two pairs were absolutely fine showing 1200 & 1218 on the meter & the last pair (isn't it always the case it's the last thing!) read 0.
Wiggling the wire suddenly gave a reading of 1200.
Continued wiggling made & broke the connection.
Replacement from the place in the above link who were excellent, 24 hour delivery.

You will need to put the rotor back on to test after cleaning, there's no other way you can check run the engine.
Bought one of the copies of the proper Mercury tool for removing the rotor on mine, under £20 IIRC but I learnt a long time ago that sometimes it's best to get the right tool to avoid breaking stuff & it also serves as the engine lifting tool should I ever want to take the engine off complete or the powerhead.

Don't know about the glue.
Perhaps you'd be better off with an epoxy as I'm not sure what sort of heat there is which might melt hotglue?

Must admit I'm not fully Ofay with electronickery devices but fortunately the manual is written in simple language that even I could (eventually!) follow.

Thanks, I wonder if it would be worth speaking to them (CDIelectronics.co.uk)

[paintman]

Nothing to lose.
They might well have some suggestions.
There was a very good 'how to' instruction leaflet came with the new part & also of interest that there are differences between the tests (and expected results) for the Mercury ones and CDIs own so that's now stuck into my manual.
The instructions covered tests & expected results for both.

You might find the USA parent company's website of interest.
www.cdielectronics.com/about/

[markS]

Ah, yes I thought I had seen the site before. I did find their manual but for the 90A 2 stroke they only had dates up to about 10 years before my model, and the tests didn't seem to make much sense.

Do they sell aftermarket CDIs, is that their main business?

[paintman]

They sell a lot of electronic stuff. Best have a browse.

[markS]

Well this is a real hum dinger, pretty peed off with it all now.

I had a friend pop in today, he's never touched an outboard but been rebuilding land rovers for best part of 50 years, and fairly handy with wiring.

We ran through all the same tests to get readings while sharing an exquisite mug of Kenco.

Get this... charge coil reading came out at 22,000 ohms, despite SPARKING. WTF?! Tried again and again, around 22k every time. After an hour of reading wiring diagram and generally pi55ing around, we connected fuel and let it rip. Fired up, ran for 10 minutes without a hitch.

His attitude was then "you must have had a bad connection and you've fixed it somehow, that engine is running perfectly!". I can't swallow that, even though it could of course be true. Firstly 22,000 ohms on a coil which the service manual says should be 80 ohms, secondly I can't take kids a few miles offshore for some Pollack with any kind of confidence!

In all seriousness, I don't think I will be doing much boating for a while. I can't bring myself to stump up for a stator or CDI when both could be perfectly fine.

I have it booked in with a Yam agent next week (booked weeks ago). I can't afford to waste a penny right now, and my friend said i should cancel that as they won't be doing any more than we did today as far as testing goes. I am not sure that's true, I'd be paying for his experience rather than knowledge or electronic expertise, i.e. he just thinks of something based on past experience that we wouldn't. But in all honestly I'd be paying for some kind of peace of mind (if he didn't find a fault) when I likely won't get any

Will have to have a serious think tomorrow.

Really grateful to the help and support from you guys here, and a huge thanks to beamishken for such a kind gesture to send me a CDI to test with. I haven't connected it, and dont see much point now as the CDI seems to be fine (was for ten minutes today). I will get that back in post probably later this week once I know whether boat is getting a tarp thrown over, or going to the shop for some professional diagnostics.

Cheers all

[Davie]

from service manual 2010 you should have between the brown - red 191-288. Between blue - red 64-96.

I just had a 75 running (same electrics) after warm.

brown- red 251 blue-red 75




from a scrap engine in bits brown-red 263 blue-red 75.


Ye need a stator i would say

[Davie]

Originally Posted by beamishken

Should be able to see the no with it insitu but it may have a cable cover you'll need to remove to see it that one is mega expensive £500 ish but a 6h2 one which fits the 60/70 is available as a copy for about£80 looks almost identical too

75-90 one is over £1000 now inc the vat!

[markS]

Originally Posted by Davie

from service manual 2010 you should have between the brown - red 191-288. Between blue - red 64-96.

from a scrap engine in bits brown-red 263 blue-red 75.

Ye need a stator i would say

Thanks very much Davie. Definitely a bad charge coil here then.
I'll PM you