two ignition coil questions

[johnreidb]

i am working on a 1985 johnson 15 hp with manual start and tiller handle. i can crank it up and run it around the lake. then i go back to the dock, i turn it off, and it won't re-crank with a warm engine. bad coil, right?

i checked the resistances on the two coils. the primary winding resistances are 0.3 ohms and 0.4 ohms. the manual says that they are outside of the normal range; they should be about 0.1 ohms. the secondary winding resistances are within the normal range at 256 and 273 ohms.

now for my question: if the previous owner mounted the coils with hardware store washers on both sides of the coils, could they be poorly grounded? should i replace the coils, or should i remove the washers? does it even matter?

thanks in advance for your help,
john.

p.s.- i don't have access to a neon tester or a DVA meter at the moment, and compression is 112 on both cylinders.

 

[Rick.]

Re: two ignition coil questions

I don't think the washers would matter one way or the other. I'd remove them just because they aren't necessary. I would recommend taking a spark tester out with you next trip and when it is giving you the symptom test right then and there for spark on both wires. Then you will know your getting it or not. As for your ohm tests if your checking them cold you may get a different reading when they get warm. Again I think a spark test will tell you a better story. Your compression is great. What seems a little odd is that you seem to have full power going back to the dock and then it won't restart. Normally if a coil is the problem it will fail as soon as it gets warm and will fail before you shut down your engine. That leads me to think your problem isn't with the coils but a spark check will help determine that. Best of luck. Rick.

 

[tx1961whaler]

Re: two ignition coil questions

Losing both coils simultaneously? And they both come back at the same time?
It sound like the issue is prior to the coils......

Johnson/Evinrude Alternator Driven CD Ignitions 1978-1999
Two Stroke/Except Ficht
Two Cylinder Engines

No Fire at All:
Disconnect the black yellow kill wire and retest. If the engines now has fire, the kill circuit has a fault-possibly the keyswitch, harness or shift switch.
Check the stator resistance. You should read approximately 500 ohms from the brown wire to engine ground. (See DVA Charts).

Check the DVA output from the stator. You should have a reading of at least 150V or more from the brown wire to brown/yellow (while connected to the pack).

Check the timer bases resistance from the black/white wire to the white/black wire. Reading should be 10-20 ohms or 38-42 ohms.

Check the DVA output from the timer base. A reading of at least 0.5V or more from the black/white wire to the white/black (while connected to the pack) is needed to fire the pack.

Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to fire properly.

Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the readings are low, disconnect the orange wires from the ignition coils and reconnect them to load resistors. Retest. If the reading is now good, the ignition coils are likely bad. A continued low reading indicates a bad power pack.

 

[johnreidb]

Re: two ignition coil questions

thanks guys.