1995 Johnson 150 OceanRunner

bartnich · Apr 9, 2012

I have a 1995 150 Johnson Ocean Runner. After i run it at 3000 to 4000 Rpm for fiftenn minutes or so, then stop and fish for a while, go to restart it, it revs up to 2000 to 3000 rpms and sounds like it is running on three cylinders. I have had the powerpack replaced, along with the plugs. it is not the cold start idling for a while and then drops down to normal idle, it just acts erratic. If i let it cool down for a while it will run fine again, or if i crank it an quickly put in gear and get on plane it will run fine.

boobie · Apr 9, 2012

Re: 1995 Johnson 150 OceanRunner

Sounds like the OSI Sensor.

bartnich · Apr 9, 2012

Re: 1995 Johnson 150 OceanRunner

Is something a mechanic should able to diagnose at a shop? Because i don't think they run it long enough to replocate the conditions. Heat, load, etc.

boobie · Apr 9, 2012

Re: 1995 Johnson 150 OceanRunner

OMC did make a tester for them but it didn't work worth a dam. I've always just replaced them on gp's if I had a prob like you have. If you have a good mechanic he may let you try one to see if it works and if not take it back off. I know I would.

bartnich · Apr 10, 2012

Re: 1995 Johnson 150 OceanRunner

Have you ever seen or heard of this problem before?

OutOfControl · Apr 10, 2012

Re: 1995 Johnson 150 OceanRunner

bart,
It sounds as if your motor is going into S.L.O.W. mode, and the primary cause would be overheating. From your other posts it seems that you have eliminated the overheating issue and have narrowed it down to an electrical or ignition problem.
The only other ways for your motor to go into S.L.O.W. mode is via a bad "blocking diode" or the power pack.
Here is a testing procedure for a '98 J150 which may be applicable to your motor.

S.L.O.W. warning system and Blocking Diode test.

boobie · Apr 10, 2012

Re: 1995 Johnson 150 OceanRunner

How can it be going into SLOW when he first starts it up and and it revs to 3000rpm ??

OutOfControl · Apr 10, 2012

Re: 1995 Johnson 150 OceanRunner

"...it revs up to 2000 to 3000 rpms and sounds like it is running on three cylinders."

boobie,
The above statement was from the original post by bartnich. It sounded to me like a classic case of S.L.O.W. mode kicking in. He later stated that he has already replaced the powerpack and plugs. If in fact the motor is going into S.L.O.W. mode and it is not caused by the temperature circuit or the new powerpack the only remaining culprit is the blocking diode.
I linked him a simple test that would rule it out and thus avoid him throwing more parts at the problem.

boobie · Apr 10, 2012

Re: 1995 Johnson 150 OceanRunner

OOC. I've seen the OSI sensor do this on 60 *motors. OMC's answer was sometimes the eyes in the sensor would get "crossed" and this would happen.

SparkieBoat · Apr 10, 2012

Re: 1995 Johnson 150 OceanRunner

CDI recommends replacing the black plug wires with the new inductive gray ones and replacing the Optical sensor when you change the power pack, and running only QL78YC plugs. I have replaced good working power packs with new CDI pack and plug wires and sensor and gained 300 RPMs at WOT. even if it is not your sensor, keep your old one for test purposes.

bartnich · Apr 26, 2012

Re: 1995 Johnson 150 OceanRunner

here is a video of whats happening. enjoy.

SparkieBoat · May 1, 2012

Re: 1995 Johnson 150 OceanRunner

have you replaced the OIS sensor yet?? If you want a dependable motor, my recommendation would be to replace the power pack, optical (OIS) sensor, and new gray plug wires, all from CDI ( boatfix.com ) . then before you install the new parts you should do DVA test on your stator and regulator, if they are good I would not replace them. you could try only replacing the optical sensor, but I spoke with a CDI tech and he said if your replace the power pack or the sensor they recommend replacing both so that both are CDI brands. and a new set of QL78YC Champion plugs at .030 gap. it will be a good investment in your motor and should fix your problems and end the guessing. If you want to your could go to the CDI electronics site and call their support line, they were very helpful to me.

bartnich · May 2, 2012

Re: 1995 Johnson 150 OceanRunner

I have not replaced the OIS sensor yet. I made the video, posted it, showed it to mechanic along with this thread. We will see what he comes up with. thanks for your recomendations. I will post any progress.

smead · Jun 4, 2012

Re: 1995 Johnson 150 OceanRunner

well, what happened. I posted similar problem with year older motor. My rpms max a little higher than yours as posted. Did the replacement of these components solve it?

bartnich · Jun 9, 2012

Re: 1995 Johnson 150 OceanRunner

I convinced the mechanic to look at this thread along with the video. He then went out and replicated the problem and low and behold....replaced the OSI sensor. All is well. Thanks to all who looked at my post! now i am going fishing.

boobie · Jun 9, 2012

Re: 1995 Johnson 150 OceanRunner

Maybe you should reread post # 2 ? LOL

SparkieBoat · Jun 9, 2012

Re: 1995 Johnson 150 OceanRunner

looks like you nailed it boobie

1995 Johnson 150 OceanRunner

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