Mariner 40 magnum sudden no spark

Seak

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Aug 24, 2016
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Hello I recently purchased a lund with a mariner 40 magnum electric start with controls. It had sat for 8 years so I rebuilt the carbs and got the motor going in the driveway. At home with the motor running I noticed that it didn't seem like the rectifier was charging ordered a new one but isn't in yet. Took the boat to the harbor to try it out. Fired right up but couldnthe get it to idle down adjusted carbs and throttle then it wouldn't start for a while didn't seem like a fuel/carb issue but kept messing with adjustments....then after more fussing around it fired up. Ran it out of the harbor and ran around for 20 mins, ran great. Shut it off and on a few times, no issues. Then decided to pull start it, it fired up first pull with key on then I turned the key off to kill tho motor. Long story less long haven't been able to get it to start and there is no spark. What could cause a sudden or intermittent loss of spark. Tried disconnecting kill switch a tilt swith still nothing. Disconnected controls and jumped starter and nothing. Time to check stator, switch box,....etc. anyone have any ideas. Could the stator and switch box be intermittent and then just die or would they just die?
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Kind of grey here but here goes:

Electric start engines use switched 12v to power things you want to turn off when not using the boat. On engines around the year 2000 (my personal reference point) the ignition key, when ON or START sends out power via a purple or red with a purple stripe wire, to distinguish that power from direct battery power which is red. If your ignition circuit uses switched power and you pull the remote elect. plug you have disconnected your power source.

On the same engines, the engine is stopped by killing the triggers which is the black wire with a yellow stripe or vise versa....one color is kill triggers the other operates your fuel enrichment/choke function; I forget and no longer have a manual.
 

Seak

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Joined
Aug 24, 2016
Messages
3
Disconnected the kill triggers (black and yellow) at the switch box and got the motor to run. With key on and the cowling kill switch entirely disconnected the motor would die when I touched the black and yellow ring connector to its terminal lug on the switch box. This leads me to believe that the key switch is having issues or there is a ground somewhere in the wiring. However after a few cycles of starting the motor and killing it by touching the kill trigger connector to the switch box terminal it decided to lose spark again even with the kill connector off. The leads me to believe that I have another issue in my key switch or wiring and in the stator, trigger, or switch box. Where can I find reliable information for trouble shooting these components with a digital multimeter. I do not have a dva. I was going to order the selection manual but read that it was garbage. Seems odd that the issue is intermittent and when it decides to have spark it runs very well.
 

Texasmark

Supreme Mariner
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Dec 20, 2005
Messages
14,544
If you have determined that part of the ignition switch is bad then suspect other parts to be bad too. Your running your engine OK for awhile and then quitting tells me that the heat generated in the switch by doing so has exposed more problems with it. Replace it and move forward.
 

Seak

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Joined
Aug 24, 2016
Messages
3
Would the ignition switch cause a no spark situation or just no crank?
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
In OFF the ign switch shorts out the triggers via the black/yellow stripe wire. In ON-START is (should) supply power to the ignition system via the purple/red purple stripe wire. If either is not doing it's job, ignition is dead.
 
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