Help with poor running 1989 Johnson 90...

First off, I appreciate any help or recommendations you guys can provide. I am a car guy and know just enough about outboards to get one to start.

I have a 1989 Johnson 90 that I picked up for my 17ft Bass Tracker. Guy I bought it from says it runs great, yada, yada, yada. Anyway, at first I did think it ran ok but I took it out on the water and it feels like it has a miss and it is terribly inefficient. Burns gas about as fast as I can put it in it. The boat runs at about 40mph with three adults so I think it is probably making correct power. Compression is 110 on the lower cylinders and 120 on the top. Ignition switch was bad and has been replaced with a new one. After running it for more than a couple minutes, either on the muffs or in the water, it won't shut off with the key. In fact, it runs better with less miss when I turn the key off. It seems to idle down some when I do this. Sometimes I have to pull the fuel line to get it to die and sometimes it does it on its own. I did try grounding, I believe, a black/yellow wire at someone's suggestion and it did nothing. I started looking at power packs and noticed that my motor has older style power heads, 1987 I believe as it has two packs. There is a sticker on the motor bracket and ID marks on the top of the motor that confirm that it is an 89 model. I have seen elsewhere that it is somewhat common to have an 89 motor but 87 heads and power packs. Anyway, one of the packs looks to be spliced in so I checked the part numbers and the spliced one is 582811 and the other is 583110. The second one appears correct through research and the first one is from a 1985 model 90. Will running two different packs cause the issues I am having? I was gonna replace the older pack just to see, but they are a little expensive to just throw at the motor. Once again, thanks for any help.

Forgot to add that the VRO has been removed and it has an "old school" fuel pump on it. I don't remember the model off hand but I do know that it was the correct one for the size of the motor per two different repair shops.

Re: Help with poor running 1989 Johnson 90...

Sorry I can't help you with the running issues you have but I am very interested in the identification info you have. A little while ago on this forum I and several others tried to id my motor from photos etc but I couldn't find the id plate on the tilt bracket. (MIA !) The closest we could get was '86 90hp. You say you found "ID marks on top of the motor" Where is it you actually spotted those numbers ? That would be of great help to me if you can help. Perhaps you could look up my old post, something like "UFO Johnson" and check out the photos. If you can help me ID my motor I would be grateful. Cheers !

Re: Help with poor running 1989 Johnson 90...

The last production year for the dual power packs was 1987. Somehow it seems unlikely that the prior owner would have gone to all the trouble to replace the 89 engine's wiring harness with an 87 vintage electrical harness. But it will work on your engine. Would be nice to know what the round core plug says on the top of the block. See picture. Yours may have a valid model number stamped on that plug. Possible that the key switch in the control box is causing you problems. They do go bad, esp if they have been rained on for many years. Once the engine is running, you could do a test by unplugging the main control box harness (the red plug under the cowling) and see if the engine runs any better. That isolates the key switch. The engine should keep running just fine. The fact that it does not turn off may indicate the ground at the key switch is "open." When the key switch is turned to off, the key switch grounds the power packs, normally shutting off the engine. While the (dual) power packs looked pretty much the same- the connectors did change over the years, perhaps why the pack was spliced. That could be part of the problem. I'd be inclined to replace that 582811 with the correct one, another 583110. Spliced connectors just don't work well in marine applications.

Re: Help with poor running 1989 Johnson 90...

I hate to tell you this on gas comsumption....I own a 90hp myself and done everything possible to try and tame its thirst for fuel. Come to find out that is the one downfall on these motors. No matter what you do to em they like the fuel. It has to do with the porting on these engines

Re: Help with poor running 1989 Johnson 90...

deebury said:

Sorry I can't help you with the running issues you have but I am very interested in the identification info you have. A little while ago on this forum I and several others tried to id my motor from photos etc but I couldn't find the id plate on the tilt bracket. (MIA !) The closest we could get was '86 90hp. You say you found "ID marks on top of the motor" Where is it you actually spotted those numbers ? That would be of great help to me if you can help. Perhaps you could look up my old post, something like "UFO Johnson" and check out the photos. If you can help me ID my motor I would be grateful. Cheers !

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See the post below your original one above. There is a plug on the top of the block, I believe it is a freeze plug, but it has ID marks on it. I was lucky as far as the sticker on the tilt bracket. It was literally just barely hanging on when I got it so I was able to snatch it before it came off. I didn't find the ID info on the motor itself until very recently, but it does match the sticker from the bracket.

Re: Help with poor running 1989 Johnson 90...

emdsapmgr said:

View attachment 180792The last production year for the dual power packs was 1987. Somehow it seems unlikely that the prior owner would have gone to all the trouble to replace the 89 engine's wiring harness with an 87 vintage electrical harness. But it will work on your engine. Would be nice to know what the round core plug says on the top of the block. See picture. Yours may have a valid model number stamped on that plug. Possible that the key switch in the control box is causing you problems. They do go bad, esp if they have been rained on for many years. Once the engine is running, you could do a test by unplugging the main control box harness (the red plug under the cowling) and see if the engine runs any better. That isolates the key switch. The engine should keep running just fine. The fact that it does not turn off may indicate the ground at the key switch is "open." When the key switch is turned to off, the key switch grounds the power packs, normally shutting off the engine. While the (dual) power packs looked pretty much the same- the connectors did change over the years, perhaps why the pack was spliced. That could be part of the problem. I'd be inclined to replace that 582811 with the correct one, another 583110. Spliced connectors just don't work well in marine applications.

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I don't know how to upload pics, but my plug reads "J90TLCDC J7138589." This matches the number on the sticker located on the tilt bracket. I did go ahead and order another 583110, as I figured there is the potential for the different packs to have different outputs, which could cause symptoms like a miss as one bank would be firing differently than the other. Hopefully it will arrive by the weekend and I can try it out. When you say control box, I am guessing you are referring to the plastic box on the very back of the engine? And the red plug is the very large plug on the side? I will try to unplug the red plug and see if that makes a difference. I may have a chance to do it tomorrow evening if I get home early enough. For some reason the neighbors frown upon a 2 stroke engine running late at night :/

I really appreciate your advice!

Re: Help with poor running 1989 Johnson 90...

Your engine is a 1986 Johnson 90 hp. That's from the model number you found. You can see the original factory exploded parts diagrams for your engine at this factory website: epc.brp.com. Interesting that the factory parts list does show a 1986 90 hp engine with two different power packs of exactly the same part numbers on yours. It's for another model-perhaps a commercial model. Your engine takes 2 power packs of part number: 583110. No, not the plastic box at the back of the engine-that's for the power trim. To test the engine without the key start switch in the circuit, you will unplug the throttle/shifter/control box by unplugging the red plug under the cowling.

Re: Help with poor running 1989 Johnson 90...

System Match shows the 583110 supersedes to 777623

Re: Help with poor running 1989 Johnson 90...

583110 is still a current part. 777623 is an anode/insert.

Re: Help with poor running 1989 Johnson 90...

I had it running and it had a fast, choppy idle. I turned the key off and the motor idled down some and appeared to smooth out a bit. I unplugged the red harness and the motor idled back up and ran like it did with the key on. Not sure what to make of that. I am gonna pull the ignition switch to ensure it is hooked up correctly. I did order another 583110 power pack and new plug wires, but won't have them until this weekend. Very puzzled, not only about why it won't shut off, but also about why it seems to run in almost a fast idle mode with the key on.

Re: Help with poor running 1989 Johnson 90...

Your engine has the dual power pack setup. I had a similar V6 dual power pack engine-and replaced one pack. On my engine, once the key was shut off, the engine tone changed, but the engine kept running. Discovered my replacement pack (it was a used pack from Ebay.) was not responding to the kill signal from the key switch. The one pack shut off, the replacement kept firing one bank of cyls and the engine kept running. If I turned the key back on, the engine tone changed again, as the other power pack stated firing the other 3 cyls. I replaced the pack in question and everything was back to normal. You may have a similar situation-it could be power pack related.

Re: Help with poor running 1989 Johnson 90...

emdsapmgr said:

Your engine has the dual power pack setup. I had a similar V6 dual power pack engine-and replaced one pack. On my engine, once the key was shut off, the engine tone changed, but the engine kept running. Discovered my replacement pack (it was a used pack from Ebay.) was not responding to the kill signal from the key switch. The one pack shut off, the replacement kept firing one bank of cyls and the engine kept running. If I turned the key back on, the engine tone changed again, as the other power pack stated firing the other 3 cyls. I replaced the pack in question and everything was back to normal. You may have a similar situation-it could be power pack related.

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Thanks for your post. This makes total sense now, as I think you have described my problem exactly. The "idling down" that I am experiencing when I turn the key off is apparently me shutting off two of the four cylinders. Now my only concern is how much smoother it seems to run with the key off. Apparently the side that has the bad power pack is running better as there really isn't any miss. The side that is shutting off must have something going on with it because I have a miss when that side is running. Hopefully the replacement power pack arrives soon and I can plug it in so I can eliminate the no shut off issue and see if I can isolate the miss. I do have new wires coming as well and the ones that are on the motor are pretty old and dry, so I may get lucky and just have a bad plug wire. Will update once I change those parts out. Thanks again.

Re: Help with poor running 1989 Johnson 90...

1FASTLASER said:

I hate to tell you this on gas comsumption....I own a 90hp myself and done everything possible to try and tame its thirst for fuel. Come to find out that is the one downfall on these motors. No matter what you do to em they like the fuel. It has to do with the porting on these engines

Click to expand...

I have a 1985 V90 and don't think the fuel consumption is that bad, but I don't run WOT that much and it's mounted on a tinny.