'84 Merc 75hp no spark at all

[kenburkeen]

Hello all, I am at a complete loss on getting this outboard running. I initially thought it may be a bad stator. It passes the ohms test according to specs from CDI, but not the repair manual. Here are the numbers:
blue to blue/white 6000 ohms this is within the parameters on both CDI sheet and manual

red to red/white is 120 ohms cdi says it should be 60-150 but the manual says 56-76 ohms

I have disconnected the rectifier and spark did not return
I disconnected key switch and attempted to remote start, but spark did not return.
I disconnected the black w/ yellow kill switch wire but no luck.


I doubt every coil went bad at once, but this problem is driving me nuts.
Flywheel looks good.

Any help would be GREATLY appreciated!! Ken

 

[mbranton]

Re: '84 Merc 75hp no spark at all

replace the switch box

 

[zorak]

Re: '84 Merc 75hp no spark at all

Do NOT start throwing parts at it. Nobody takes returns on electrical parts.You cannot properly test a stator with an ohmeter. There can be one winding shorted which will not affect the resistance reading very much at all but will affect the voltage output tremendously. You will have to either build or buy a DVA adapter to hookup to your ohmeter. It has a capacitor that charges up so you can read the true output voltage on a stator because the stator output is pulsed. If you use only an ohmeter the voltage readings will be all over the place. I think i would go with CDI's test procedures and specs as the do make replacement parts and should know what they are doing.I don't think you can test every function on a switch box but you can eliminate everything else by testing. Good luck.

 

[Timmy222]

Re: '84 Merc 75hp no spark at all

I would take it in to someone who will run a few tests with the proper equipment while you wait. Most likely they wont charge you to test for spark. I ran into a problem with mine and tried everything then took it in for a quick test and he pinpointed it right away. Good luck !!