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Johnson 70EL76D Terminal Block Wiring

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SlabSlayer

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I have a '76 Johnson 70HP (70EL76D) that I inherited. It has been running for years with only a slight hesitation on WOT from neutral. Last season, it got worse to the point that the hesitation was permanent and it would not achieve more than 6 or 7 mph. I replaced the plugs and all 3 coils with CDI replacements in the offseason. This season, it began with the same. It would run cold off the dock, but once warmed up, it just wouldn't pull itself out of the water. I took it to one of the last remaining mechanics who would work on it and was told it had a blown power pack and one of the new CDI Coils was bad. He replaced both with used OEM. It ran better, but was still sick. After two outings it again wouldn't achieve more than a slow troll. I have pulled the flywheel, stator and timing ring look good. Replaced the power pack and all 3 coils with Johnson OEM New parts. When I was checking the wiring harnesses for possible rub shorts, I noticed a discrepancy in the Terminal Block Wiring. Not sure if it has always been this way or if my mechanic had some reason to change it. I tend to believe it has always been that way but the looks of it.

In the Seloc '73-'91 Johnson Outboards Repair Manual, Appendix p. A-18, it illustrates the yellow\gray wire from the Stator connected to Terminal 2 with the Gray wire from the Remote Control Assembly. However, on my Terminal Block, this wire is connected on Terminal 3 with the Yellow\Gray wire from the Rectifier & Lead Assembly.

Should I move it? Is this a normal variation in the wiring? What issues would present if left this way? Could that be a part of the problem? What might happen if I move it?Screenshot_20230729_120504.jpgScreenshot_20230729_115714.jpg
 
2 & 3 are the same thing because of the jumper. Anyway, grey is the tachometer signal and that has nothing to do with your problem.

Make sure you are not working with a junk motor. Check compression. check for water intrusion into the cylinders.
 
Sorry for my ignorance. Please elaborate on the "Jumper". I am not seeing any jumper wire.

Motor has been great for years. I checked compression, as did the mechanic, and all three pass spec within a pound or two of each other.

Water intrusion... What am I looking for?
 
Can you not see the metal clip that connects 2 and 3 ????----What are those compression numbers ?-----About 140 PSI ?
 
I can see it now that you pointed it out. I did not notice it before. Had to blow up the pic. Poor eyesight and poor lighting in the shop are getting worse. Thanks for that though. So the wiring is not an issue.

I will have to put it all back together and test the compression again. I don't recall exactly where they landed last season when I tested it. Will post back when I get that done today. Thanks for your help!
 
fdrgator said:
2 & 3 are the same thing because of the jumper. Anyway, grey is the tachometer signal and that has nothing to do with your problem.

Make sure you are not working with a junk motor. Check compression. check for water intrusion into the cylinders.
Click to expand...
So it appears that the compression is an issue. 82, 82, 76. Mechanic paperwork states he tested it at 108, 114, 102. Not a good sign.
 
Water ingestion into the cylinders is a well known problem with those motors. Any overheat condition warps the exhaust cover baffle plate causing water to squirt into the cylinders' exhaust ports. If not noticed and repaired immediately, result is complete destruction of the powerhead.3 CYLINDER EXHAUST PLATE..jpg
 
fdrgator said:
Water ingestion into the cylinders is a well known problem with those motors. Any overheat condition warps the exhaust cover baffle plate causing water to squirt into the cylinders' exhaust ports. If not noticed and repaired immediately, result is complete destruction of the powerhead.View attachment 30849
Click to expand...
Thanks! I haven't yet torn apart the exhaust manifold. Not sure if it would do me any good with compression as low as it is. Might be in for TMR. $$$$!
 
racerone said:
Remove cylinder head.-----Post pictures of the cylinder walls.-----Then we suggest a path forward.
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That may be the next step. I am going to scope the cyls and check the walls for damage. If they are scored, someone else gets a parts motor. I'm not up for a rebuild. I've been toying around with the idea of a 4 stroke replacement anyway.
 
racerone said:
Remove cylinder head.-----Post pictures of the cylinder walls.-----Then we suggest a path forward.
Click to expand...
I have scoped the cylinders and was expecting a bit more carnage than I found. But then again, I only have a frame of reference from 4 stroke industrial and automotive. Perhaps these marine 2 strokes are more intolerant. That's where I need an experienced eye.

I have uploaded photos for:

Cyl #1

Cyl #2

Cyl #3

Thanks in advance for your experienced feedback and assessment!
 
One sign of water ingestion is pistons that look like they have been steam cleaned. Those pistons look mighty clean to me.
 
Yes. Yes they do. Might also be all the Marine Seafoam that has been going thru it before I got it. He told me he put some in every tank. Even the head domes were spit polished.
 
racerone said:
Motor is worn out and needs a teardown.
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We are in agreement. I predicted "complete destruction" from water ingestion way back in post #7, just another way of saying "worn out". And the bore scope confirms it. I'd be highly surprised if all the bearings in the crankcase are not destroyed also. Another word come to mind too. "Junk".

BTW, we didn't have nice stuff like cameras you could stick down through the spark plug holes, into the cylinders, back when we were learning these things. Nor computers. Nor Internet. My first job was after school and Saturdays for a Martin Outboard dealer. We've come a long way, Baby.
 
You worked on those ----" Pressure cookers " ?----Actually those Martins were a really well built motor for the time.----Have a bunch in my shed.
 
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