'73 OMC 9.5 Help (No Ignition After Repairs/Maintenance)

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kstrayhorn

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I've got a '73 Evinrude 9.5 Sportwin that I've been working on for a friend because I'm apparently the most mechanically inclined person he knows. It's a recent purchase for him, so I never saw it run, but according to him it ran rough and didn't want to idle (in retrospect he says he thinks "rough" was only running on one cylinder). In any case, the last time he took it out it wouldn't start at all, so he took it to a shop for diagnosis. They told him it needed a carb rebuild, new fuel pump, and new points & condensers. So I did all that for him along with a new stop button (wires were old and the jackets were completely gone), new fuel line fitting (old one was cracked, affecting fuel pressure), and new spark plugs. After all of this work, still nothing, and it's not even trying to turn over.

Here's everything I've adjusted, tried, and figured out on it:
Set, checked, and rechecked points at .020".
Gapped and regapped plugs at .030" and I've even tried overgapping the plugs to try to get a hotter spark.
Compression seems to be low, but acceptable at around 65psi in each cylinder (maybe just under, but my gauge is from the 60s and difficult to read while cranking).
Both plugs are getting spark outside of the cylinders, although one appears to have stronger spark than the other.
Tried every adjustment on the rich/lean needle from seated to 2.5 turns out.
Fuel is for sure getting to the bowl and to the cylinders, and fuel pressure is holding.

The 2 things that concern me as potential sources for the problem are:
1) When I crank it with no plugs in the cylinders, a nice mist of fuel comes out of the bottom plug hole, but nothing out of the top. Even when holding a finger or hand over the top hole, it doesn't even get wet. However, the reed valves seem to be clear and if I crank it with the plugs in, then pull them to inspect, both cylinders seem to be wet. I could be wrong, but my explanation for this is that fuel demand runs on an as needed basis as controlled by cylinder pressure. In other words, under compression and with ignition, pressure in both cylinders will draw fuel in, but without compression, there is not enough pressure to draw fuel into the top cylinder.
2) As I mentioned, one plug seems to have a stronger spark outside of the cylinder, even when switching the plugs to opposite leads. While I can't test the spark under compression, I believe this is the most likely source of the problem. After inspecting the coils, both have cracks, but one is more severely cracked than the other. Perhaps it is coincidence, but the most damaged coil coincides with the top cylinder, which had the noticeably weaker spark. However, both coils test good (~3600 ohms) across both the primary and secondary windings. My thoughts are that one or both coils is/are arcing off the flywheel under compression, weakening the spark and not allowing ignition.

So, my questions and where I need help:
Is my hypothesis concerning bad coils and arcing off the flywheel a sound one although there is spark outside the cylinders, there is no clear evidence of arcing, and the coils test good?
Is there any way I can further test the coils to confirm that this could be the problem? (I didn't want to buy a spark tester as the cost of one is almost that of a new coil).
Is there anything else I can do or test to see if the problem is somewhere else?
Is there enough evidence here to tell him to put new coils on it, or should I send him back to the shop before telling him to spend more money?

If I can get y'all any more info on it, please let me know. I look forward to any thoughts/responses and, as always, I thank you all for any input or help.
 
Cracked coils can be arcing anywhere.....replace them. You may be able to look up testing outboard coils on a Mercotronic on YouTube somewhere to see what happens to cracked coils under load. Hint....don't hold your hand anywhere near a crack.
If the condensers are old.....replace them as well.
Cut your plug wires back and leave about 1/8" wire exposed when you shove them back into the coil pilots. Hopefully you will get OEM coils which come with new coil boots for the mag plate.
Secondly, the compression is marginal. See how it runs. It may never be a fast starting or great idling engine with that compression. Worse when hot. Know that going in.
Third, the only pressure a fuel system will hold is between the closed needle and seat and the check valve in the primer bulb. Do not expect the primer bulb to hold pressure when the engine is running.
 
Thanks for the reply. I've told him to order new coils, but I can almost guarantee he won't get OEM. New points and condensers were installed when I did all that work last week.
If he wants, I'll check the compression again when I have someone else to hold and read the gauge. There's quite a bit of carbon buildup on the piston heads and he plans to do a seafoam treatment or something once it's running, so I'll for sure check compression again after that.
What I meant by fuel pressure was that after priming the bulb and cranking it once or even moving the cracked fitting at all the bulb would lose all pressure, but that's been fixed with a new fitting.

Thanks again
 
Check out leeroysramblings.com for a good read. Any cracks in coils=bad. Must have continuity across your points when nothing is connected to the screw and they are closed (false ground reading if everything's connected). Your spark should be able to jump a 1/4" gap.

Sent from my SM-G900R4 using Tapatalk
65 psi is acceptable. I think you're partially right on the compression drawing fuel in but it's on the other side of the piston in the crankcase. With 65psi in both cylinders I doubt it's a ring issue but could be upper crankshaft seal.
Also you'll have better luck with a emergency start cord wrapped around the flywheel for compression and spark readings (faster flywheel than the pull starter.)
I could be wrong on some of this but these have been my experiences.
 

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