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1999 Johnson 90 possible timing problem

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  • 1999 Johnson 90 possible timing problem

    Hello everyone I have a 1999 Johnson 90 2 stroke not sure the exact model but I know it is the one that has 2 thermostats as I found out the other model doesn't have. Well on to the problem, I got this outboard used and it has some time on it so I was expecting possible issues. So I ran it on the water for a good 4 hours and all seemed well, other than the fact that the throttle cable needs to be adjusted as you have to about push it all the way to the dash to get a response of full throttle all at once, and rather quickly with little room to adjust to a half speed as opposed to a lower just over idle speed. The same case with reverse and getting to neutral is a problem in itself. That's a little over view but I don't think that is my true problem. I ran it for 4 hours and not much problems till I was heading back in. I gave it full throttle and it bogged way down and the outboard started shaking violently at that time white steam also appeared so I quickly backed it back down. Got it back to the landing and started to go through some tune up steps, first off I put a a compression test on the plugs and all the numbers seemed about right on so I'm not to worried about a cracked block. or blown head gasket. My next step was to replace the 13 year old thermostats to make sure they were working properly. I also replaced what looked to be the original plugs and set the to .030 gap. Re-fired up the engine in the yard on the hose and ran it after it had been sitting a few days and it cranked up and ran at full throttle strong but I was noticing a skip still. My next step is the wires, after testing them the dangerous way with a screw driver all seemed to have spark, I still plan to replace them when I have the cash however the skipping and motor vibration continues. I imagine the distributor cap could also be causing this skip/vibration and popping noise, and it was also suggested that the carburetor may need cleaning. I also suspect that if the distributor is not the problem the next thing I am afraid of is the Timing chain/belt I'm not sure what this engine has, I have worked on a lot of car mechanical issues but this is my first experience with outboards, and I'm not an ASE certified tech I have gotten most of my experience working with real mechanics and picking up things here and there. Any thoughts or suggestions in this matter, I'm not sure if my diagnosing steps are being done properly as I'm thinking the only things that could be causing this are the wires, distributor or god forbid the timing which I hope to rule out. One other thing I do have a stream of water coming out the top so I think that may rule out the impeller, however after running it today I noticed the water was hotter than usual and the foot was very warm to the touch which I havn't noticed before.
    Thanks for the overlook again and any advise may be helpful and appreciated. lol one last thing it was also suggested that my fuel line from the on board tank running to the engine may have a pin hole leak as the bulb never tightens up completely after squeezing, if this is the problem which I guess it could be, let me know I'm just afraid I am either overlooking something or possibly missing some steps in diagnosing this issue properly and was hopping one of you could possibly enlighten me.
    Dan

  • #2
    There is no distributer or timing belt. If you are getting spark, then I would not suspect ignition. You should change the water pump impeller as a precaution. If it has been sitting for long time, I recommend removing and cleaning the carburetors. The timing is all electronic and controlled by the throttle linkages. You should also replace both cables, I do not believe that adjusting will help.
    Regards
    Boats.net
    Johnson Outboard Parts

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    • #3
      Thanks for the quick response I will make the water pump impeller and carburetors my next step on the list!

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