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1990 115 Inline 4 Issues

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  • 1990 115 Inline 4 Issues

    Need some help here guys. Engine is a 115 1990 inline 4.

    Here is what I have done so far. Engine had sat for some time unknown. Engine had no spark on 2 cyl. Replaced stator with Mercury Red Stator. Got spark. Cleaned carbs. Engine started first crank. Engine starts and runs on the water hose just fine. Put it into the water and it would not start. Finally got to start by covering intake of a carb. with a rag. Once engine was running would not come up to speed. It would idle fine but wouldnt go past 1/4 to 1/2 throttle while in the water.

    Spoke to someone he recomended to check exhaust that it may be clogged. Took apart and nothing there. Also reccomended to check reed valves. I replaced with new.

    Now engine still starts and runs fine on water hose. Starts easier in the water but still have to cover carb. intake with rag. Choke doesnt seem to be enough. Engine will still not get passed about 1/4 to 1/2 throttle. Can choke it a bit while running and pick up some more RPM but it will not stay.

    Any help would be great.

  • #2
    Do you have test harness/keyswitch so you can eliminate the boat harness from the engine. Check for spark when the boat is in the water. I had a Yamaha that did exactly what you are describing. It turned out to be the boat harness. You need to find out what you're losing when the boat is submerged in the water. My guess would be spark.

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    • #3
      I do not have a test harness I could use unfortunately. I will have to check spark once its in the water but I dont think that is the issue. Seems more fuel related to me at this time.

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      • #4
        If choking it helps then must still have plugged passages or jets inside carbs. Make sure compression is good.
        Regards
        Boats.net
        Mercury Outboard Parts
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        • #5
          Originally posted by boats.net View Post
          If choking it helps then must still have plugged passages or jets inside carbs. Make sure compression is good.
          Compression is 127 lbs in all 4. I will clean the carbs out again and re check all passages and jets.

          Could the fuel pump be in the equation as well? When gassing the engine I can see fuel spray into the top cyl. but not the bottom 3. Also with the engine running the fuel pump should be pumping fuel right? I dont seem to have much fuel at all coming from the pump??

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          • #6
            i am having the same problem with my 1990 115hp inline 4. Did you determine the problem? My boat is a 1990 SeaRay 16'9"...

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