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Johnson 6 hp won't start

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  • Johnson 6 hp won't start

    Hi, I recently purchased a 1975 Johnson 6 hp. I used to have a 77 model so I'm pretty familiar with this motor. It will not start or even try to start. Compression is 70 in both cylinders. I cleaned carb and put a rebuilt kit in it. I replaced coils and points and set them correctly. I've got good spark on top and bottom. I can't get the motor to even try and start. I've even tried starting fluid just to try and rule out a fuel issue. Even with starting fluid motor does nothing. Any ideas what it could be?

  • #2
    What counts as "good spark?" If it won't pop with starter fluid, something is amiss.


    • #3
      Are the wires going to the correct coils?


      • #4
        The sparks are blue and loud and I can see them in the daylight. I sent the wired back to the coils they were before. I guess it's possible that they are backwards? If they are right though and I switch them could I damage anything?


        • #5


          • #6
            I flipped the wires and still nothing.


            • #7
              Does spark jump a gap of at least 1/4" , yes or no ?


              • #8
                Yes. He spark does jump a 1/4 in gap


                • #9
                  Might retest the compression, screw-in type tester. Should run with 70 or 80 lbs. Test with plugs out, pull it over four or five times until the needle stops moving.


                  • #10
                    If the condensers are bad I would have no spark or weak spark, correct? Any chance it's condensers?


                    • #11


                      • #12
                        If measuring spark with an open air tester, and getting 1/4 inch (assumption), maybe you have incorrect plugs or plug gaps. The oem plug would be a Champion J4, I believe, gapped at .030.

                        Did you measure spark with an open air tester, and what plugs are you using?


                        • #13
                          Spray some gas/oil mix into the cylinders and see what happens.


                          • #14
                            He already tried starting fluid.

                            ​Check to see if the timing is right, or if there's a sheared flywheel key.


                            • #15
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                              From what you said it sounds like either timing is off or it's really flooded.

                              My guess is the timing is way off. Pull the spark plugs and the flywheel, then turn the crank until the piston is at Top Dead Center. The points on that cylinder should be just starting to open.