So we have any one good with outboard electrics, I have a yamaha f40 that won't start and I'm getting a weak spark.
So far I have tested the stator plate as I think that is where the issue is and I'm getting a reading of 6ohms on the power could 25v ac and 679 ohms on the charge coil. Can anyone offer any pointers but I think it's shot
Not being a smart-ass but with Yamaha's as dependable as they are..when something go's wrong, unless a reply from someone who's had the same problem/fix, Go to the manual. Actually quite odd a Yam will muck-up without some kind of help. I run a small merc, but I know mercs and some o the merc weak pints (coils) namely. But with an engine as dependable as a Yam...go to the service manual or take it to a reputable yam service shop. Good luck.
I'm not saying it's not the plate, but have you checked the HT leads?
Granted my lump of premix burning history uses older school HT tec, but I have found on two occasions the connector in the lead eventuasllty comes loose form the cable itself.....
Also have you changed the plugs- I meggered mine for a laugh & was gobsmacked as to how much less resistance between the business end & earth there was on a 1YO plug.... One I tried had been in the lawnmoeer for years was almost dead short for the High voltage......
I have put new plugs in for the sake of it just in case, but I will check earths but I don't think that comes into play when checking the resistance of the coils on the stator
i have had a look at the manual and there are fault finding tips, i just want to make sure im testing right 
