Johnson 28 SPL no spark

Discussion in 'Boating and Boat Rigging' started by ajkulish, Apr 11, 2018.

  1. ajkulish

    ajkulish

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    Trying to track down my electrical issue here. I have compression and fuel, but no visible spark on the old screwdriver test. I believe it has something to do with my tether switch but I am not sure.

    Every key ignition diagram (attached) ive seen has shown just two wires connecting to the tether switch. One black, one black/yellow. However my boat has a black and 2 black/yellows. I rewired all the accessories on the boat since it was rigged all jenky, and everything is now very clean. I did not touch the keyswitch/ignition wiring. When looking at the tether switch, it appears one black/yellow and the black wire both go to the appropriate M terminals on the key switch. The other black/yellow however was not attached to anything. I assumed it was a common ground, but i may have assumed wrong.

    I left the wire disconnected and cranked the motor. Doing this resulted in the starter turning well but the solenoid disengaged after a moment so that the starter gear and flywheel were no longer in contact. I then tried grounding the mystery black/yellow wire and the motor would crank, and the solenoid would NOT disengage like before, and the motor cranked well as long as i had the key turned. I believe when i pulled the tether off the switch, i had the same symptom as the first scenario (starter solenoid would pull gear from flywheel).

    Not sure where i should start on this, but i assume the tether is the culprit. Where does the third wire go? This could be CDI but i would like to verify all other paths before purchasing one. Let me know if you have any thoughts. Thanks!

    (including pics in case anyone wants to draw and point or anything)
     

    Attached Files:

  2. ESOX

    ESOX Staff Member Super Mod Mods

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    I did not touch the keyswitch/ignition wiring. When looking at the tether switch, it appears one black/yellow and the black wire both go to the appropriate M terminals on the key switch. The other black/yellow however was not attached to anything. I assumed it was a common ground, but i may have assumed wrong.
    Both Blk/ yellows connect to same terminal on ignition switch. The other end of one goes to the kill switch (lanyard switch) the other end of the second goes to motor.
     
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  3. ajkulish

    ajkulish

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    I was with you at first, but am a little confused. If both black/yellow go from the kill switch to the same M terminal on the key switch, why not make them one wire? Theoretically i could connect the "mystery black/yellow" to the other black yellow 1 inch down the wire and achieve the same effect, no?
     
  4. ESOX

    ESOX Staff Member Super Mod Mods

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    No, you have two black AND yellow wires (Like yellow with black stripe usually, but yours look like black with a yellow stripe) coming off one terminal on ignition switch, one goes to motor, other goes to kill switch.
     
  5. ajkulish

    ajkulish

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    Look at my picture though, i have two black/yellows coming from the kill switch.
     
  6. ESOX

    ESOX Staff Member Super Mod Mods

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    OK, so how many blk with yellow are on ignition switch? If there is only one, my bet would be that the "mystery wire" goes to the motor, same difference, common terminal on switch or coming out of modular plug at kill switch, as long as it isnt being grounded by kill switch it tells the motor it can spark........
     
  7. ajkulish

    ajkulish

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    I will verify when I get home, but I believe I do have both shown in the diagram.
     
  8. ajkulish

    ajkulish

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    The strangest part is that if the mystery wire is not grounded, the solenoid that pushes the gear on the starter vertically will not function properly. It will crank the flywheel for a second, then drop down and continue spinning without turning the flywheel. If it is grounded, the motor will crank as long as I tell it to.

    I can find nothing on a johnson kill switch having 3 wires. Perhaps it is an aftermarket kill switch that is not connected properly.
     
  9. ESOX

    ESOX Staff Member Super Mod Mods

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    Odd, I give up.
     
  10. ajkulish

    ajkulish

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    Would disconnecting the black and black/yellow wire from the ignition switch bypass the kill switch?
     
  11. piketroller

    piketroller

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    If you believe the wiring diagram is correct, then just trace all your wires to see which ones don’t have the right connections. Since you said the boats wiring was a mess, someone might have done a hack job on this circuit too, with the colors not being right, or the wrong colors spliced in somewhere that you don’t know about. After you have verified where everything is either through continuity testing or other means, let us know what isn’t wired correctly.
     
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  12. Aaronjeep2

    Aaronjeep2

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    I have the same excact motor let me go look at the wires I bypassed everything.
     
  13. Aaronjeep2

    Aaronjeep2

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    I put a toggle switch and still have the key ignition. I took both purples that go to the ignition and spliced them together then took the yellow/red wire and hooked that to the toggle. I turn the key to on position then hit the toggle to turn motor over.
     
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  14. Aaronjeep2

    Aaronjeep2

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    When the battery is low that's what the starter dose.
     
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  15. ajkulish

    ajkulish

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    Well, my initial thought was correct. This has to be an aftermarket kill switch with the same color wires, but do not correlate to the same things. I unplugged the key controls under the cowl and it started first pull with a rope. I reconnected, and then cut the toggle completely out, and it fired that way as well.

    Well, for a bit. The water in the bucket was disgusting by this point, and the motor would only idle for a bit. All signs point to needing a carb rebuild, but of course i cant find the proper carb rebuild kit (carb number 398348). Hopefully a good cleaning will do the trick.
     
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