1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

[Jay238]

Hey guys, been searching for two hours on here and seem to have come to the conclusion that the 1995 Johnson 15HP has a lot of issues. Here is mine. The engine will start fine and take off onto plane on the first start of the day. After that, I can barely keep it running. When I try and give it throttle, it sounds like its "barfing" and sputters out. I then have to start it in neutral and rev it up high (smokes like a chimney), let it idle down and shift into forward. For it being a 15HP at full throttle, it feels like a 2hp. Recent maintenance from a marine shop was new water pump impeller, spark plugs, gas, and lower unit oil. Gas was mixed at 44:1. Any ideas? Yesterday, it could troll all day and now it wont even idle. I'm annoyed with this engine big time. The idle seems very hard, as in the motor shakes from one side to the other as opposed to smooth. I pulled the prop and there was no line or debris behind or wrapped up in it. Any help will be greatly appreciated.

 

[ondarvr]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

If I had only one guess I would say you have a bad coil. Frequently as a coil goes bad it will work when the motor is cold, but as the coil warms up it will fail.

The correct ratio is 50:1, not that's it's a big deal.

 

[Kiwifisher]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

These are usually pretty reliable motors that run forever. My only suggestion would be to start with the basics, fuel, spark and compression. As ondarvr says, coil most likely the issue. Next I'd clean or even rebuild the carbs. None of that however will help much if you don't have good compression. If you can lay your hands on a manual, start a logical fault finding process. You'll eventually nail it down. Good luck.

 

[steelespike]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

Perhaps one of the plug wires is loose.
You might pull the plugs see if they are tan or black or if one is amazingly clean. look for evidence of water present
droplets on the plug or perhaps a touch of rust.
Water intrusion sometimes produces lots of white smoke that dissipates quickly.
2 stroke smoke is bluish and lingers.

 

[Jay238]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

These are usually pretty reliable motors that run forever. My only suggestion would be to start with the basics, fuel, spark and compression. As ondarvr says, coil most likely the issue. Next I'd clean or even rebuild the carbs. None of that however will help much if you don't have good compression. If you can lay your hands on a manual, start a logical fault finding process. You'll eventually nail it down. Good luck.

How hard and how much does a new coil cost?

 

[w2much]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

How recent was it at the shop? Did it run well when they had it last? Coil about $40., 20 used.

 

[Jay238]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

It was at the shop the day before I took it out. They said it ran fine at the shop.

 

[the machinist]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

My guess is that it could be only running on one cylinder which could be the coil but I doubt that. By the way, those coils are made molded as a dual pack not individual as with the pre 93 motors.

To check this, have it running & pull one plug wire, replace it & pull the other. If it dies on either, the one it dies on is the only one firing. Now this could be a loose/corroded wire connection from the coil or even inside the spark plug boot, or even as simple as a fouled spark plug.

These motors can start & run on only one cylinder, but have no power.

Check the spark plugs, if you are trolling a lot & using a slightly richer oil mix you could be fouling the plugs, which could be contributing to it not firing at the spark plug. Also be sure that you use marine fuel oil (TCW-3) for your mix.

 

[Jay238]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

Here are a couple pics if the plugs I just pulled. The darker one was the bottom plug. They were bought new yesterday

http://i131.photobucket.com/albums/...8DDB13E-4594-000002B19D820E9E_zps8033367f.jpg
http://i131.photobucket.com/albums/...73CCC95-4594-000002B1930004A4_zps78c40b54.jpg

 

[Jay238]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

Today testing on the hose it is running perfect, what gives?

 

[nwcove]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

take a hair dryer and heat up the coil pack while its running to see if there is any change. hose/barrel running is alot different than real world conditions. jmo

edit: if you choose to do that, be aware of the hazard of electricity and water !!!

 

[ondarvr]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

"Today testing on the hose it is running perfect, what gives? "

Typical of a bad coil, that doesn't mean it's the coil for sure, only that it fits the symptoms of a bad coil.

 

[Jay238]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

Well, replaced the fuel line and primer bulb with a new one. Ran PERFECT for 35 mins on the ears/hose. All gears, revved up hgh etc. Took it to the lake this evening, start it up and put it in forward..barf barf die. I then pull and pull and pull and pull to get it started again. Starts, shifts into forward fine but feels again like it is a 2hp motor instead of 15. Changed both plugs again, fresh gas mixed at 50:1, motor pees water perfect with the new impeller, does not overheat, and gets spark. Running out of ideas.

 

[ondarvr]

Re: 1995 Johnson 15HP Two-Stroke- Dies on throttle, idles bad

There is no way to tell if its running correctly on the hose, there is no load and no back pressure, it can sound good even running on one cylinder, testing it in the water is the only reliable method. If you don't want to get a new coil ( I don’t like buying parts if I don’t need to) buy an inline spark tester to see if it's actually firing under load. Or pull one plug wire at a time and see if dies, if there is no change in how it runs when you pull one off, you found the problem.