Re: Testing Johnson Ignition Coils
If you're simply checking the continuity and readings of those circuits, a common multimeter will do the job... has always worked for me. You don't say what type coil you're speaking of so I'll list a few.
(Magneto Capacitance Discharge Coils - Continuity Test))
(J. Reeves)
Check the continuity of the ignition coils. 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.
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.
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.
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(Battery Capacitance Discharge Coils - Continunity Test)
(Joe Reeves)
Remove the primary wire the screw type terminal. Remove the coil and unscrew the HT wire from the distributor cap.
Connect the black lead of a ohm meter to the HT wire, then with the red ohm meter lead, touch the ground wire of the coil.
Then touch (still with the red lead) the wire that normally attaches to the powerpack output lead. You should get a reading on both touches (contacts). If not, check the HT wire by unscrewing it from the coil. After removing the wire, the check can be repeated using the internal threaded prong within the coil instead of the HT wire. Poor or no continuity of a coil is one reason for erratic or no ignition and/or s/plug fouling.
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(Regular Magneto Coils - Continuity Test)
(J. Reeves)
Checking the continuity of the ignition coils....... Have the ohm meter set to High Ohms.
Remove the primary wire from points. Remove the coil ground wire. You do not want either of these wires touching anything.
Connect the black lead of a ohm meter to the spark plug boot terminal, then with the red ohm meter lead, touch the ground wire of the coil.
Then touch (still with the red lead) the primary wire. You should get a reading on both touches (contacts). If not, check the spring terminal inside the rubber boots of the spark plug wire.
If there is no continuity between the secondary circuit (spark plug) wire and the primary or ground, remove the coil from the armature plate, then check the continuity directly between the prong within the coil (prong that the plug wire connects to) and the primary and ground. Poor or no continuity of a coil (or plug wire) is one reason for weak spark, s/plug fouling, or no spark.
