1975 johnson outboard problems

Hello,
This will be my first post here. I am a marine mechanic, shipwright of over 25 years.
I haven?t worked on too many outboards, my uncle gave me this thing, 1975 50 hp Johnson. I have rebuilt the power head, 30 over pistons, seals, bearings, rebuilt the carburetors and finally just replaced the coils tonight, last week I took it out for a good run.
It ran great!!! That was with ?repaired cracked coils? (used epoxy) 25 minute run ? throttle 18 to 20 miles per hour, it was great! Never owned my own boat before, just worked on everyone else?s.

We got to our destination, it started rattling and missing, farting, putting etc. first thing I found was loose starter bolts, starter was rattling about, ok tighten down, silicone nuts no problem, start it up? hard to start. Try to limp home farting missing no power 1/3 throttle all the way home, at about 3 miles an hour, could not get her up to speed.

Got it home, dismantled carbs, found some debris. Ok start it up runs better but a miss that is intermittent, replaced coils at that point, still same problem, would the power pack be at fault or something else? And this thing has always been hard to start from day one, even before I rebuilt the darn thing. What should I investigate before I buy more parts. Thanks, Cam Vancouver Island Canada.

Re: 1975 johnson outboard problems

did you torque the flywheel to specs? if not it may have sheared the woodruff key, and that throws it out of time.

Re: 1975 johnson outboard problems

did you torque the flywheel to specs? if not it may have sheared the woodruff key, and that throws it out of time.

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that?s a possibility, I was going to pull the flywheel today to inspect pickups, would the starter loosing off its mounts cause this? You would think, there would be teeth shattered though, I shall get back to you after. Thanks

Re: 1975 johnson outboard problems

i got 50hp johnson dont now the year it has a electric shift in the lower unit am going to part it out if you need any parts let me now

Re: 1975 johnson outboard problems

Well to my surprise, good guess by the way, tashasdaddy broken woodruff key, one week to get the original, ran down to my auto parts store with a micrometer, found one, started up like a new engine for once. Just waiting for the tide to fill the bowl, at our little inlet cove and take this antique wood boat for a good run. I was working on several engines at the same time, might have not torque, flywheel bolt. :redface:

Hey rick74631 I don?t really need any parts, I already have a spare gear box and a few other bits and pieces, but thanks for the offer, we also have a guy here on the island that collects and works on really old out boards, big collection!!! If anyone is looking for hard to find parts let me know, I shall give him a shout.

Re: 1975 johnson outboard problems

There a reasonable chance the "auto parts key" will shear. Get a BRP key, which is properly hardened and, again make sure to torque to the correct value and make sure the tapers are clean and dry (no oil, etc.) Enjoy.

Re: 1975 johnson outboard problems

wilde1j said:

There a reasonable chance the "auto parts key" will shear. Get a BRP key, which is properly hardened and, again make sure to torque to the correct value and make sure the tapers are clean and dry (no oil, etc.) Enjoy.

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So, I have never heard that some woodruff keys are of a forged nature, at any rate I grabbed four of them, from the auto parts store, just to keep me busy, also ordered the factory one, 10 bucks it bloody should be forged. Thanks again, I shall try to offer my years of experience were I am needed on this site.

Re: 1975 johnson outboard problems

Not forged, but hardened.

Re: 1975 johnson outboard problems

agree 90% chance the standard key will shear. so you do not get stranded again, when you get the new key, go ahead and change it.