1973 Johnson 25 HP // Sat for years, not starting now

creece09

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Jul 28, 2011
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Hey Iboats forum,

I inherited a ‘73 Johnson 25 HP outboard. It sat in a covered shed for years but was reportedly cranked and ran just fine every so often (the last time being over a year or so before I got it).

I am able to pull the cord and it turns but doesn’t start, try to start, think about starting, or seem to even know what the word ‘start’ means.

I squeeze the gas cord bulb until it gets hard, have the handle in the start position, tried different levels of having the choke in/out, changed spark plugs, ensured it was in neutral, and prayed over it.

The few boat repair shops I contacted said they don’t work on motors that old. If you have a shop or person you would suggest in the north Alabama region I’m all ears.

Hopefully with some help, tips, and guidance I can get it going myself but I’m open to taking it somewhere. If I do take it somewhere to get it fixed, I’d need to weigh the cost of repair versus a new motor.

Thanks for appeasing me,
CR
 

F_R

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Jul 7, 2006
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28,195
Really? They don't fix them in Alabama? Forgive me, but that kind of surprises me. Guess I'm getting too old also.
 

lindy46

Captain
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Nov 27, 2008
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3,886
Start with the basics:
Check compression. Should be 100psi+ on both cylinders and even.
Check spark. Should jump a 1/4" + gap with a snappy blue-white spark.
 

tomhath

Master Chief Petty Officer
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Dec 5, 2007
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814
Those motors are simple enough for even an inexperienced mechanic to work on with basic tools. Plenty of help will be offered here if you want to give it a go yourself.

Taking it to a pro will probably cost more than you want to spend; their time is worth the same whether they're working on a $300 motor from 1973 or a $15k motor from last year
 

RaisedByWolves

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Oct 4, 2017
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90
You need fuel, compression and spark in that order.


For small engines I usually start by dribbling fuel into the carb to see if it even wants to run as a clogged carb is the no1 reason a motor like this wont fire.

If that gets you no where check compression and spark.
 

54bobby

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Dec 12, 2010
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todays mechanics don't work on them because they can't plug it into a diagnostic reader.
 

racerone

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Dec 28, 2013
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They do not work on them because usually owners will complain on the cost of repairs to old motors.-----The shop gets a bad reputation for charging too much.-----Owners with $60,000 boats say ---" thank you "----- even to a $1000 repair invoice.-----As stated you have an " old motor " but the time to fix it is all " brand new time "------Oh---These 1973 models are easy to fix if you want to learn.-----So , when you pull the choke on is it staying on after pulling the cord once ??
 

creece09

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Jul 28, 2011
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Hardwater - I didn’t try that. It would be a simple fix and completely worth a shot. I’ll try it out.




F_R - I just hope when I get old the doctors don’t say the same thing about me!




Lindy - those are good starting points. I know I can rent a compression checker from the local auto parts store and see what I get with it hooked up.




Tomhath - I’m up for working on it, I’m slightly mechanically inclined. Slightly. I think my biggest perk on this side is being able to find information and translate it to practicality. Getting it running would also score me major points with the wife and father in law, right??




Raised by wolves - to put fuel into the carb, open the round flat flap and squirt some fuel into the area behind it, the float bowl? How much should I put in there?




Racer one - I totally understand. It’s business decisions, on their part and mine. Labor cost is the same applied to me and someone with a 350 Yamaha. If it costs us both $2k to repair our motors, it makes fiscal sense for the Yamaha owner but not necessarily for me.




The choke stays the same. The wheel turns when I pull it but that’s the only thing that happens. The one thing that might be happening is the bulb gets softer but honestly that may just be placebo of me wanting it to work.
 

racerone

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Dec 28, 2013
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36,030
??----What wheel turns ?-----Does the choke flapper close and stay closed when you pull on the cord , yes or no ?
 

creece09

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Jul 28, 2011
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Whatever wheel/gear the pull cord is attached to. I didn’t look at the flapper itself, just the choke engager (the little knob you pull out or push in). And it stays out if it was out when I pull the cord or stays in if it was in when I pull the cord
 

tomhath

Master Chief Petty Officer
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Dec 5, 2007
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814
Start with the easy checks first. Go to a good auto parts store, buy a spark tester (one that you can adjust the gap, not just a flashing light). They'll usually loan you a compression tester. A cheap VOM meter is also good to have when troubleshooting ignition.

Take both spark plugs out and use an electric drill on the flywheel nut to spin it to test compression. Do the same with the plugs out to test for spark. My guess is that you won't have spark because the points need to be cleaned - a very simple and routine process.
 

creece09

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Jul 28, 2011
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Hey Tom,

i checked for both spark and compression, compression was good, however there was no spark. You say the points might need to be cleaned, are these the points inside the female spark plug connector that is going from the engine to the spark plug? What’s the process for cleaning those? A spark plug cleaner and wire brush?

Thanks!
 

lindy46

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What were the compression readings? If no spark, you need to remove the flywheel. That is where the points and condensers are. That motor has external coils - they could also cause your no spark situation if they are bad. I'd clean or replace points first and see if you get spark. If not, it's easy to replace coils on that motor.
 

creece09

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Jul 28, 2011
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Racerone - ah, I see. I misunderstood and thought it meant connection points for the spark plugs.

105 on the compression

With the the help of the neighbor we tried to get the flywheel off. No luck. Couldn’t even get it with a puller.

Went ahead and ordered two ignition coils because either a) that may miraculously fix the problem or b) they needed to be replaced anyways and aren’t too expensive ($30 a piece).

Thanks!
 

creece09

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Jul 28, 2011
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Also, tested the ignition coils with a multimeter

(because apparently you can do that? Or so says the internet, but I don’t understand how they would get a reading if they aren’t connected to power. I suppose not understanding mechanical stuff like that is why I’m on a forum asking for help haha)

but it never gave a reading.
 
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lindy46

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Nov 27, 2008
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You need a harmonic balance puller, not a jaw-type puller, and some grade 8 bolts. If the points are bad or dirty, changing the coils won't help.
 

creece09

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Jul 28, 2011
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We finally got it off and got access to the points. The points were dirty and corroded so we cleaned them. Put everything back together but they are not sparking. The points that is. There is a bit of disagreement. Is a battery needed to run this motor? I know for sure the starter is busted , but for crank pulling...
 
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