Johnson oceanrunner troubles?

[brdm]

I have a 1998 Johnson Oceanrunner 200 HP motor that I am having a few problems with. The last time I was out, I noticed that it was struggling to plane off. Once it did plane off, it seemed to run fine. But, getting on plane was a struggle. It would idle fine and all. Then the next day when I went to start it off the hose to flush it, it did not want to idle right and kept shutting off. When it was running I noticed that it was not loud as usual like it was not hitting on all cylinders. Even when I reved it up some it was not running as loud and deep sounding as usual. I tried an easy fix of changing plugs and the same thing happened. After I shut it off, I noticed some nasty grey ooze coming out of the prop exhaust. I know this is alot of symptoms to diagnose, but, I would appreciate any ideas on the culprit. I have made a call to get on a local mechanics waiting list, but was wondering if anyone here might have some ideas.

 

[tashasdaddy]

Re: Johnson oceanrunner troubles?

start with the basics, the mech is going to. check compression and spark on all cylinders, you have 6 cylinders and 3 carbs, what did the plugs look like, when removed. dry light brown, black and dry, black and wet. brown and oily. post these results.

 

[Chris1956]

Re: Johnson oceanrunner troubles?

TD - I believe that motor has six carbs.

If you find out that you only have spark to one side of the motor (3 cylinders only), check the temperature sender on the port side head. This controls the S.L.O.W. system which kills spark to 1/2 the motor.

 

[tashasdaddy]

Re: Johnson oceanrunner troubles?

chris, you may be right, i no expert on the big boys, but they run the basicly same way. you are right on about the slow sensor.

 

[brdm]

Re: Johnson oceanrunner troubles?

Well, I have finally got around to checking on the engine again. I checked for spark on the cylinders and found three of the six not firing. When I am standing at the back of the motor the right side top to bottom are not firing. Does this sound like the temperature sender? Where is this located and any info on how to check this out? Someone also mentioned a shift interupter switch. I am going to try and pull this shift interupter switch tomorrow to see if it is sticking. Any more ideas? Thanks.

 

[brdm]

Re: Johnson oceanrunner troubles?

bump

 

[Chris1956]

Re: Johnson oceanrunner troubles?

BDM, It is likely to be either the SLOW system or the Shift Interrupt switch.Warm up the motor and then disconnect the port temp sensor and see if it hits on all 6. If not, then disconnect the shift interrupt switch

 

[brdm]

Re: Johnson oceanrunner troubles?

Thanks again for all the information. I think we have found the culprit. I made some more checks today and I unplugged the shift interupter switch and tested again for spark on the starboard cylinders. All cylinders are now sparking a good blue spark. I pulled the switch off and it appears to be stuck in the down position. I tried to clean it and get it to free up with no luck. I am going to make some calls and try to find one locally and be back up and running by the weekend.

 

[angus63]

Re: Johnson oceanrunner troubles?

If your idle rpm is below 700 rpm or so, you can run without it. Only affect is it may take a little effort to come out of gear if the rpms are above 750. My 175hp idles at 650 and I do not notice any difference with or without it.