1997 Johnson 15 hp dropping a cylinder??

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Richard A. White
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1997 Johnson 15 hp dropping a cylinder??

Postby Richard A. White » Sat Mar 31, 2018 12:13 pm

1997 Johnson 15 hp dropping a cylinder, then dropped spark completely. I changed to new plugs, it would start, but not run right, shut it off, after 3 minutes of running and bottom new plug was light tan, but top looks as if it has never fired.

So how do I go about determining if it is the coil failing or the power pack?

I switched plug wires, but still no go....

And no it is NOT mine...LOL

Thanks

Richard A. White
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PM T2
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby PM T2 » Sat Mar 31, 2018 2:54 pm

its only a 20 year old motor. Its not even a classic yet. You're the Sheriff, you should know better.

PM T2

fleetwin
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby fleetwin » Sat Mar 31, 2018 3:38 pm

!@#$ it! I just typed a long response and the website/computer froze up. lost it...OK, one more time....
Always start with the simple stuff...Check the coil grounds and pack ground using an ohm meter on the low scale, reading should be as close to zero ohms as possible. Next, it is a good idea, to eliminate the stop circuit from the system. Yes, not likely that a faulty stop switch would affect just one cylinder, but never say never.
Next, I would inspect the ignition wiring and disconnect the five pin connector coming out from under the flywheel to the pack. Any signs of melted/chafed wiring, perhaps a botched previous wiring repair? It might fight you, but you can wrestle it apart carefully. Have a look at the pins and sockets, any misaligned/partially pushed out of the connectors? Do not spray lube/oil/grease inside the connector before reconnecting the two halves, this could cause a partial short that will cause trouble down the road. Use rubbing alcohol inside the two halves to easy connections, this will evaporate and cause no problems.
Next, pull off the coil primary leads from the coils. These connections are a big trouble area, especially in salt water. The connections get loose, rusted causing ignition headaches. I would clean up the terminals, the crimp down the connectors slightly to ensure a tight fit/good connection. Go ahead and use grease on these terminals, won't cause problems here. Now, I would swap the coil primary leads. Put the top primary lead on the bottom coil, and the bottom on the top coil.
Check for spark again.
If #1 still does not fire, then you have some sort of coil problem, perhaps a messed up secondary wire/boot/terminals.
If #2 does not fire with the leads swapped, then you have a pack or sensor problem....
Let me know what you find...D

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Richard A. White
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby Richard A. White » Sat Mar 31, 2018 3:45 pm

While I enjoy the older motors, RBM's to be specific, because he is family I agreed to look at this.

His plugs looked horrible, and I had some J4C in house, so I put 2 new ones in... Same problem, So I switched the wires, and no change, So I wil see if I can find anything obvious with the coil.

As for the stop circuit, I find more reasons to effing hate "some" engineers.... $150 for an effing kill switch????? a simple $2 would do the job.... anywho his kill switch does not function at all. Is there any way to replace it with something cheaper that will do the job?

Thanks

Richard

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Mumbles
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby Mumbles » Sat Mar 31, 2018 4:08 pm

Richard A. White wrote: Is there any way to replace it with something cheaper that will do the job?



It's amazing what BRP wants for their parts and they aren't even platinum plated. :o

Any cheapo lanyard kill switch mounted on the side will do the same job. These ones are also push to kill.

https://www.ebay.ca/sch/i.html?_from=R4 ... h&_sacat=0

fleetwin
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby fleetwin » Sat Mar 31, 2018 4:25 pm

I hear ya buddy....The prices of cheap plastic crap helped kill OMC for sure...Try snaking the darn things out of tillers and twist grips also, now that is some real fun....At least the newer ones got away from the stop switch in the end of the twist grip...
Let me review what I think you are telling me...You swapped the coil primaries and the number one/top coil still does not fire?? If so, this would indicate some sort of coil problem...Check the darn primary connection and the secondary/plug lead. Those funky boots/connections get rusted messed up easily...
Coil primary resistance should be about .1 ohms, this can be real tough to read on many ohmmeters.
Secondary resistance should be about 275 ohms, plus/minus 50ohms...
If in doubt, compare your readings with readings on the #2 coil that is firing.
Perhaps the top coil is arcing to ground, this might not show up on an ohm meter test...

outbdnut2
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby outbdnut2 » Sat Mar 31, 2018 6:40 pm

I've replaced kill switches on a couple of 1991 15 HP Johnsons with generic ones at $10 or less after seeing the $100 price tags on the OMCs. I mounted the replacement on the front panel because it wouldn't mount into the tiller handle. Most of these replacements have normally closed and normally open contacts so they will work with magnetos or electronic ignitions.
Dave

The Seachoice or Seadog inthe link below should work:

https://www.iboats.com/shop/electrical/marine-switches-battery-ignition-rocker-and-toggle-switches/emergency-boat-kill-switches-and-lanyards.html

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Mumbles
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby Mumbles » Sat Mar 31, 2018 9:05 pm

You can get them for less than four bucks a piece with free shipping in and from the USA. If you have a few motors needing them, it might be worth it.

https://www.ebay.ca/itm/8x-Universal-Bo ... r#shpCntId

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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby Richard A. White » Sun Apr 01, 2018 4:55 pm

Well, I pulled thew coil and gave it a good look over... hmmm what y'all think...cracked coils...LMAO
20180401_164951.jpg
20180401_164951.jpg (1.28 MiB) Viewed 374 times

Richard A. White
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fleetwin
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Re: 1997 Johnson 15 hp dropping a cylinder??

Postby fleetwin » Mon Apr 02, 2018 9:28 am

Well, I see the cracks in the potting, which may or may not indicate a problem...I don't see any indications or arcing though. Wipe off the coils, and have a close look all over the coils for signs of arcing. Did the coils check out OK on the ohm meter? How did the primary connections look? How about the plug leads/boots/terminals, did they seem OK?


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