ignition coil tested with ohm meter

[ajforno]

Hi there, <br /><br />I've looked for a previous posting on this specific topic and did not found the answer, and since I do not have a manual either, I decided to ask for help.<br /><br />I have 4 identical ignition coils in my 115 HP 1976 Evinrude , but two of them show open circuit between the spark plug cable and either of the two read leads. The other two ignition coils, show close circuit between the spark plug connection cable and either of the two red leads. My doubt is which two of them are bad? <br /><br />Thank you , <br /><br />Andrés from Chile

 

[Hooty]

Re: ignition coil tested with ohm meter

The two that are open are bad.<br /><br />c/6<br />Hooty

 

[seahorse5]

Re: ignition coil tested with ohm meter

Check the spring clip where it attaches to the plug wire. Pull back the rubber boot and make sure it is making good contact and is not rusted or corroded, then recheck with an ohmmeter.

 

[Joe Reeves]

Re: ignition coil tested with ohm meter

If you have coils whereas the plug wire appears to be part of the coil, the plug wire unscrews from a threaded prong within the coil.<br /><br />Removing the plug wire allows you to check the actual continuity of the coil itself less the plug wire.<br /><br />Checking the continuity of the ignition coils.<br /><br />Remove the primary orange wire from whatever it's connected to. It may be connected to a powerpack screw type terminal, a rubber plug connector, or it may simply plug onto a small boss terminal of the coil itself.<br /><br />Connect the black lead of a ohm meter to the spark plug boot terminal, then with the red ohm meter lead, touch the ground of the coil or the powerhead itself if the coil is still installed.<br /><br />Then touch (still with the red lead) the orange wire if it's attached to the coil, or if it's not attached, touch the primary stud of the coil. You should get a reading on both touches (contacts). If not, check the spring terminal inside the rubber boots of the spark plug wire. Poor or no continuity of a coil is one reason for s/plug fouling.

 

[Hooty]

Re: ignition coil tested with ohm meter

If the coil windings are open, is the coil bad?<br /><br />c/6<br />Hooty

 

[Joe Reeves]

Re: ignition coil tested with ohm meter

Hooty..... You are correct is stating that the two that are open are bad. The open windings force the spark to jump that extra internal gap, if the coil sparks at all, resulting in a improper weak spark.

 

[Hooty]

Re: ignition coil tested with ohm meter

Thanks.<br /><br />c/6<br />Hooty

 

[ajforno]

Re: ignition coil tested with ohm meter

Thank you Hooty, Seahorse and Joe for your precise help.<br /><br />After reading your postings, I went right to the engine and unscrew the plug wire from the bad coils just as Joe indicated. The plug wire had continuity but the secondary winding on the coil still showed open circuit. The primary winding on the coil was OK though, since I put the Ohm meter between the orange lead that comes from the powerpack and the orange with black strip that goes to ground, and I got a reading.<br /><br />I imagine that the cause of the powerpack failure was produced by the bad coils. I have ordered both coils, a power pack, and also a manual!!<br /><br />After I receive and install the new parts I will come back to you guys, thank a lot.<br /><br />Andrés