1987 Johnson 15 no spark

blufrog1

Recruit
Joined
Apr 15, 2019
Messages
5
rebuilt carb and pull starter, reinstalled both and mysteriously have no spark. Checked the kill switch, it is operating properly and checks to open, pulled the power pack and cleaned the ground, reinstalled...still no spark. It was running and had spark when last checked three days ago. What could I have bumped that would screw it up?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
37,835
Look for spark at night with a proper spark checker set at 3/8"----Daylight may have fooled you.
 

tphoyt

Lieutenant
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Jun 10, 2010
Messages
1,265
What was the reason for the carb rebuild?
We’re you having problems?
Did you use a kit and if so what kinda was it?
Maybe squirt some fuel mix in the carb and see if it will bark at you.
 

saltchuckmatt

Commander
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Jul 19, 2019
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2,652
Also, disconnect the kill wire. Switch can test fine with tester but still malfunction because of the amps going through it.
 

kbait

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Joined
Nov 13, 2007
Messages
2,462
Google: ‘CDI troubleshooting’ and grab your multimeter. Test 2 coils under flywheel at big plug with wires coming from under flywheel to cd box. If one of those coils is out of spec, no spark either cylinder. If they test good, you either have 2 bad external drive coils (rare to fail simultaneously), shorted wire from under flywheel to cd box, shorted kill wire cd box to stop switch, or bad cd box (very common). Good luck!
 

blufrog1

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Apr 15, 2019
Messages
5
Daylight proved to be the problem, couldn't see the small spark. Found it but it still would not fire. Put a small a,ount of premix in top cylinder and it fired up tight off. Ran it for half an hour whilst fiddling with mixture and eventually got so low on idle it died, and damned if it would not restart that time. It had several other times. let her sit overnight. this morning, several pulls, no firing. Removed top plug and added some premix, fired right off and stop starts ok thus far.

Reason for rebuilding carb is this is a new motor to me and the first time out I experienced some erratic operation, which after removing the carb I found to be a broken cam follower, but decided to go through the carb since I had no idea about the condition. It was pretty clean actually. I also have a water pump kit to rebuild it just because I don't know the condition and here in AZ they don't last long. I notice that while running sometimes debris plugs the pee hole and a small wire clears it immediately.

When running she seems to be a smooth little engine, but when it won't start its a bear.
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
37,835
Post your compression numbers.----And when starting do you advance the throttle to the neutral stop ?----Best to ignore the start mark on the steering handle.
 

tphoyt

Lieutenant
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Jun 10, 2010
Messages
1,265
Let us know your compression numbers and what you did to fix the cam follower.
Both very important to start for starting.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
There are two idle adjustments -- the idle air/fuel mix, and the throttle adjustment. If both are adjusted properly, the motor should idle at about 550rpm (check your manual and go by the specified setting). It sounds as if your mix adjustment is about right -- throttle adjustment might be bumped up a bit so the motor doesn't stall.

Some owners prefer to adjust the motor to stall out at the lowest idle -- If that is your preference, you may have it adjusted properly.

On the other hand (i.e., starting), I sometimes have to enrichen the mix on my 9.9s for cold starting, then return it to the leaner sweet spot for running.
 
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