Any Outboard Techs Out There? (Mercruiser Question)

[fleming442]

No compression check yet- we stopped last night after discovering that the triggers (not stators as mentioned) are different. We have to put the old trigger and stator back on to get the flywheel on to do the compression check. I suppose that will be on this evening's agenda......
I'd like to be able to measure the outputs on those, but I need the FSM for values to look for. I plan on at least testing the coil leads to see if we're getting voltage and a pulse from the trigger assembly. I should be able to get something off the 2 cylinders that were firing, anyway.
I have read some nasty stuff about voltage spikes from the regulator, but that seemed to fry coils where the defective one tested identical to a known good one. This is all assuming it will fire with the old trigger assembly.
Man the parts are outrageous! ~$250 for the trigger, ~$3-400 for a stator, ~$300 for an ignition module

 

[DRIVEN]

My brother went round and round on his outboard for 2 seasons, then his girlfriend's dad did for a year. They rebuilt the carbs twice and swapped/replaced all kinds of ignition parts. There was a new set of plugs in the glovebox that he swapped out and it ran exactly the same. Would drop cylinders and lay down under any load but would idle and free-rev just fine.
They finally bit the bullet and took it to a boat guy. The problem? Wrong plugs -- both sets. Apparently 2 stroke outboards can be finicky about plugs and his particular engine was known to only run right with the OEM plugs even though other brands and part numbers would cross as "correct" by the parts counter listing.

 

[fleming442]

I've read Subarus are like that, but it didn't seem to matter what parts I threw at it. It was always ****ed up- OEM or aftermarket. I won't rule plugs out on that alone, though.
Did some measuring tonight: from what we could find spec-wise, the stator is good, and the trigger is suspect.
Didn't bother with a compression test because the plug won't fire.

 

[Bonnewagon]

Apparently 2 stroke outboards can be finicky

Absolutely. I even go out of my way to get the real OMC two-stroke oil at my dealer guy. He sells it by the gallon- your container. My plugs stay clean all season vs the West Marine cheapola stuff I used to use. Plugs fouled several times a season with that brand. As for ignition components If I suspect a bad part I try to scrounge up a cheap used replacement on Ebay just for testing. If it cures the problem then I invest in a factory new part and save the test part as a spare. In your case if it is ignition related then the charge coil, sensor coils, ignition coils, or Power Pack are suspect. Old models combined all the coils in one huge stator assembly and it cost a fortune. Later models used individual components that can be replaced as needed. Anyway once you find the specs then you can test them all. Right now if any show a short to ground then that is conclusive.

 

[fleming442]

Just to wrap this up: after reinstalling the factory parts that came off, it hits on all 3 now. I hate it when stuff fixes itself!

 

[olds307 and 403]

I hate 2 strokes in any form, they are finicky. I want a new EFI 4 stroke for my next boat. The little light Lund I want is either Mercury or Honda, will probably go Honda. You would have to give me a carbed 2 stroke boat, I wouldn't pay money for it.

 

[Bonnewagon]

It was running pretty good, but developed a miss in the center cylinder.

So I'm guessing there was no "real" problem all along. Parts don't fix themselves. It could have been a loose wire connection, fouled plug, dirty carburetor, or bad oil mix. What sucks is not knowing exactly what was wrong and preventing it again. Is it oil injected? I purposely avoid those and prefer to mix my own. That way there is no problem with the 50:1 ratio. Outboards are VERY sensative to oil ratio. The thermostat also comes into play because the operating temp and oil ratio work in concert, just like our emissions carburetors. Olds307/403 I have an 1969 Lund 18' commercial skiff with a 1980 Johnson 35hp. What a great boat they make.

 

[fleming442]

I agree that it didn't "fix itself", and, yes, it is self mixing.