1974 Johnson 15 hp runs on 1 cyl at low speed

Home › Forum › Ask A Member › 1974 Johnson 15 hp runs on 1 cyl at low speed

Viewing 10 posts - 11 through 20 (of 20 total)
1 2
  • Author
    Posts
  • October 7, 2016 at 1:07 am #45353
    Mumbles
    Participant

      While the plugs are out, it would be a good time to check for continuity between the wires core and the small spring inside the boot. They can get rusty and corroded in there causing a miss.

      Attachments:

      October 7, 2016 at 1:23 am #45355
      timmy3131
      Participant

        I ran it tonight and pulled the cover off. The bottom spark plug was arcing between the cyl. And the 13/16 hex part that the wrench goes on. This is a new coil I installed. Could I have done something wrong?

        October 7, 2016 at 1:29 am #45356
        wedgie
        Participant

          I would change the spark plug boot if you’ve already checked the terminal and wire. I like to check the integrity of my boots by touching them and then grounding myself on the shroud 😆 😯 Makes you feel alive ! From what I’ve observed that when the boot looks all crackled, it leaks current. Some boots that look ok leak too.

          October 7, 2016 at 1:39 am #45357
          Mumbles
          Participant
            quote timmy3131:

            I ran it tonight and pulled the cover off. The bottom spark plug was arcing between the cyl. And the 13/16 hex part that the wrench goes on. This is a new coil I installed. Could I have done something wrong?

            Arcing between the cylinder head and the hex or between the boot and the hex? You might have a bad plug.

            Wedgie: Don’t you find doing that hard on the Pacemaker? When I ground myself out, all it does is make me real smart for a few moments! 😀

            October 7, 2016 at 2:49 am #45359
            PugetSoundBoater
            Participant

              I had a spark plug lead "leak" and run down the porcelain,from the boot to ground on my 76 9.9. I noticed that the boot was installed further onto the plug than the other cylinder that was behaving itself. i pulled the plug boot off,cleaned the porcelain reinstalled the boot not as far this time and the problem stopped. I guess the path of least resistance came into play in this case, the porcelain cleaning may’ve been a factor ,especially once a carbon path develops.

              "Some people want to know how a watch works, others just want to know what time it is"
              Robbie Robertson

              October 7, 2016 at 11:14 am #45366
              timmy3131
              Participant

                The spark plug boot was new when I installed the coil. I will clean the porcelain also but here is a question I have. Is there any reason why we have to use the style of plug caps that they come with and why I couldn’t use the ones that screw in the end of the coil like on a snowmobile or Atv?

                October 7, 2016 at 11:16 am #45367
                timmy3131
                Participant

                  The spark plug boot was new when I installed the coil. I will clean the porcelain also but here is a question I have. Is there any reason why we have to use the style of plug caps that they come with and why I couldn’t use the ones that screw in the end of the coil like on a snowmobile or Atv?

                  October 7, 2016 at 1:46 pm #45370
                  fleetwin
                  Participant

                    US Member

                    So, the spark is arcing between the rubber boot and the plug porcelain, is this correct? And, this is a brand new coil? Seems like we have heard this same story recently….Is this a new OEM coil, or aftermarket? In any event, I would go with Mumbles’ advice and replace the plug boot/terminal assembly. I would definitely use the OEM piece Mumbles showed us, even though it is a pain to install, don’t try some other style. How about the plugs? What kind are they? I would replace them as well, gapped at .030".
                    Unfortunately, you got the first year that OMC produced these style engines, and there were many ignition/plug fouling issues. There are about four different update kits that are supposed to alleviate this condition, but the effectiveness is questionable. This ignition system is kind of a hybrid system between a conventional magneto and the CD2 system that was introduced in 1977, there are still points under the flywheel. You won’t find too many guys that like this system. It can be made to work correctly, but everything has to be right.

                    October 8, 2016 at 3:18 pm #45435
                    timmy3131
                    Participant

                      ok I think I MIGHT have figured out the problem. The spring turned inside of the boot and It wasn’t all the way on the spark plug. I think that it ran better at high RPM because the it was putting more juice through the coil and able to jump over. I pulled the boot off, cut a bit of wire off faned out the wires and lubed it up and reinstalled it. and made sure that this time it went all the way on. I’m going to take it later to the river and try it.

                      October 8, 2016 at 3:43 pm #45436
                      Mumbles
                      Participant

                        Sometimes it’s the simplest things! ☺

                      • Author
                        Posts
                      Viewing 10 posts - 11 through 20 (of 20 total)
                      1 2
                      • You must be logged in to reply to this topic.