Can a faulty ignition switch cause weak spark?

[huntandhook]

Hello Everyone,
I am having spark troubles with my 1979 Johnson 40HP. I have checked the points, replaced the ignition coils and the driver coil, and checked the safety switch and all the wiring connections, but I am still getting a weak spark on both cylinders. The spark is a little better on the top cylinder than the lower, but neither spark is strong enough to start the motor. I am wondering if the key switch could be at fault, since I have checked everthing else I can think of. The starter motor turns when I turn the key, but the motor won't start. Is it possible that a short in the key switch could be the cuase of my spark problems? Is there any way to test the key switch? Any advice would be greatly appreciated.

Thanks,H&H

 

[imported_lorin]

Re: Can a faulty ignition switch cause weak spark?

Why not disconnect the big red plug or whatever kind of connection you have from the motor to the key switch. Then try to rope start the engine. The engine can run without being hooked up to the key switch but you'll have to choke it to stop it. Even if you don't start it with the rope, at least you can check the spark and see if it looks stronger with the plug disconnected. If you have good spark with the plug disconnected you know it's either the key switch or the kill switch on the remote control. If you have a kill switch on the motor you can also try disconnecting that and see if you have better spark.

 

[dsinger]

Re: Can a faulty ignition switch cause weak spark?

Just jump it with cables with the plug disconnected

 

[jtexas]

Re: Can a faulty ignition switch cause weak spark?

If the starter's not spinning the engine fast enough...could be battery, could be starter...how did you determine the spark is too weak?

Points on a 1979 ignition? Don't you have CD ignition?

Key switch test:
Terminal "B" to ground should have battery voltage

Terminal "B" should have continuity with:
- Terminal "A" with key turned to "On"
- Terminal "S" with key turned to "Start"
- Terminal "C" with key pushed in *and* turned to Start or On

Terminal "M" (ground - black wire) should have continuity with other terminal "M" (kill circuit - black/yellow) with key turned to "Off"

 

[imported_lorin]

Re: Can a faulty ignition switch cause weak spark?

Yeah, dsinger you have a better idea than mine. But what do you mean by "with cables"? You can jump it with a screwdriver or a little jumper wire on the solenoid.

 

[huntandhook]

Re: Can a faulty ignition switch cause weak spark?

My engine still has points because it is the commercial model. The 40HP commercial used points until 1982. The Starter cranks the motor over plently fast enough - way faster than I could ever hope to turn the motor with the rope starter. I used a spark tester to test the spark and it wouldn't jump 1/4" and there was no loud snap. My friend even held the plug to ground, and he said he could feel some current (he guessed 1000V but I think he was just talking out his ass) but I do know that It gives you a hell of a jolt when it fires at full spark, so if there was good spark we would have known. I'll try testing the key switch as jtexas suggested.
Thanks for the advice,
H&H

 

[alden135]

Re: Can a faulty ignition switch cause weak spark?

http://www.iboats.com/bbboard/bbBoard.cgi?a=viewthread;fid=28;gtid=792794;gpid=792810#gpid792810

This may be helpful