Its a Stihl fs 45 trimmer and when I hook up a spark tester to it it shows I have spark but when I take the plug out and ground it to the engine i don’t see a spark. My guess is that the coil is weak and the spark won’t make it to the plug. The plug itself looks new and I try other plugs that should work and I don’t get a spark. I did gap the coil with a business card so I don’t think that’s the problem. Also the magnet on the flywheel is not dirty or rusted

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    I think you are in the wrong forum. You already tested with other working plugs (I think with correct characteristic), so the problem is more complex for us. You get better info in the sites with people with good mechanical skills. My experience: changing the plug usually solve the problem, but only when this does not cause further problems (e.g. longer plug). Check also the connection on the black rubber cable (on top of the plug, testing/changing plugs gives also problem there): electrical cables/connectors could be damaged. Jun 26, 2018 at 9:25
  • I have a couple Stihl small engines and they are very reliable, although they can flood or over choke easily. Try opening the choke and turn it over several times, Or find a U-tube for your machine. Jun 26, 2018 at 14:52
  • Since this question isn't getting any answers here on Gardening & Landscaping, I can move it to our sister site, Motor Vehicle Maintenance & Repair if you'd like. Reply to this comment and let me know. Thanks!
    – Niall C.
    Jul 4, 2018 at 14:30


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