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older 70 hp Nissan sparking between the flywheel and starter gear

Glasspar Scott

New member
I have an older 70 hp nissan (ns70a) that was running great. Had it on the lake and it stopped suddenly, almost like I lost the kill switch. Got towed back and am working on diagnosing the problem. I ordered the service manual, thanks Paul, and went to run some tests. I had pulled off the flywheel to look at the coils and they looked great visually. I reinstalled the flywheel to run the tests while cranking the engine and started getting a good sized spark between the flywheel and the gear on the starter. Not a constant spark but almost like a spark on timing. Not what I was expecting. Pulled the flywheel back off and don't see any obvious reason for the sparking. I did not know that was even possible and was just wondering if i am missing something or did i do something wrong. I am fairly certain that one of the electrical components are what failed when the motor stopped. Not knowing the engine well enough I did not know how to test the kill switch in the water. (I now know how to temporarily bypass for diagnostic purposes) That was the first test i was going to run when I ran into the sparking issue. I have loosened and checked the ground on the starter and it looks good. Not sure if a nicked wire on the coil plate assembly would cause that or if something is hooked up wrong. There are not a lot of wires on the motor and they are all color coded so I dont think that is the problem. Any ideas would be appreciated.
 
Both your flywheel and starter should be ground, so no reason to expect that problem. You can check coils with an analog ohm meter to see if they have continuity and are not shorted to ground.
 
Ok. I have played with it a little longer and think maybe the sparking is just from some corrosion on the flywheel. I also tested out the coils and they test fine but the Rectifier or regulator is not testing correctly. So working on ordering one and will see what happens.
 
Ok, so finally got it running today. Tested the cd pack and one side tested no resistance at all so ordered a new one. Put it on the boat and still no start. Dva tested the upper coils and they showed good voltage. They also tested out correctly on the analog voltage meter. The coil that runs 290 ish tests only on the analog meter. Both of the other coils tested for the correct resistance on the digital meter i have so that was cool. When I tested the ESG it showed bad as well but was not sure I was testing it properly. Bypassed it today and motor runs awesome. plug it back in and it wont run so definitely bad. Not sure if several things went bad all at once or what happened. I do know that with the old cd i did bypass the ESG and it did not run.
 
Ok, so finally got it running today. Tested the cd pack and one side tested no resistance at all so ordered a new one. Put it on the boat and still no start. Dva tested the upper coils and they showed good voltage. They also tested out correctly on the analog voltage meter. The coil that runs 290 ish tests only on the analog meter. Both of the other coils tested for the correct resistance on the digital meter i have so that was cool. When I tested the ESG it showed bad as well but was not sure I was testing it properly. Bypassed it today and motor runs awesome. plug it back in and it wont run so definitely bad. Not sure if several things went bad all at once or what happened. I do know that with the old cd i did bypass the ESG and it did not run.

It's possible that whatever blew the ESG also blew the CD.
 
Very possible. When I had it one the water it just stopped suddenly, no sputter just great to dead stop. I am excited to have it running now to see how long it lasts.
 
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