ns70a2 need help

i went out and ran my boat today and everything was going fine the i hit a wake from another boat and my motor died. i could never get it to start again. it would crank fine and fuel delivery was fine. when finally got boat home checked to see if had spark and did not. traced wires running to coil. one set runs to esg and then magneto. there are also 2 wires that traced back up to key switch. checked them to see if were power or grounds. black wire had 12 volts and brown wire was ground. tried bypassing esg by plugging harnesses in bypassing esg and still no luck. think coil unit might have went bad. just weird how did it all of the sudden. is there any way i can test it? any thoughts that someone might have to help? thanks

Re: ns70a2 need help

You definitely could benefit from the assistance of someone who knows what they are doing here. I would suggest getting to a dealer, or someone else who is more knowledgeable with OB's than you, before you do any damage by troubleshooting. This system includes a pulser coil, trigger coil, CD unit, and ignition coil... in addition to the ESG, and of course... also has an alternator and rectifier. Methodical troubleshooting with proper instruments should isolate the problem.

The black and brown wires are for the kill switch. If the safety lanyard popped off when you hit the wave, that would kill the ignition, causing symptoms not unlike what you are experiencing.

Specifications and troubleshooting techniques are in the Factory service manual, available from any dealer.

A full wiring diagram is in the parts catalog, available on Elvin's website at http://www.internetoutboards.com/Pa... Catalog NS50C-60A-70A2 (1992) - (M256B).pdf

Re: ns70a2 need help

the safety switch that it has is never been hooked up. i have never had to install a lock in it. is it supposed to be normally open or normally closed. i dont think that is the problem due to never having it used since i got the boat. see what everyone thinks.
thanks

Re: ns70a2 need help

If you have remote control... and if the black/brown wires to the kill switch at the RC box are disconnected... likewise, if there is an on-the motor kill switch... and if the black/brown wiring to it is disconnected... then you don't need a stop lanyard attached to the kill switch.

However... if the switch(es) are in place and wired up correctly, the kill switch stops the motor by grounding out the ignition to shut it off. So, for normal running, the kill switch, with the lanyard inserted under the head of the switch, would be an open circuit.

Re: ns70a2 need help

when i checked them i could read voltage between them. what perpose does the rectifier serve. cause i see power runs to it then out to the magneto. has a white and yellow wire that runs to it. does the rectifier send power to the magneto and then it energizes it and send it out to the esg? what does the esg do? just trying to do some troubleshoot any help would be appreciated.

thanks

Re: ns70a2 need help

If you ground the kill wire (then there are zero volts between the brown and black wires), that will shut down ignition.

Regarding the rectifier... You have it backwards. The rectifier rectifies AC power into DC power for battery charging.

The ESG is the electronic speed governor.

If these concepts are getting beyond your skill set, you may want to get to a competent outboard mechanic or dealer.

Re: ns70a2 need help

got the service manuel and figured out that the recitifier is for the alt/charging circuit. how does the esg work and what can i do to test it to make sure it is working correct?

Re: ns70a2 need help

hunkajnk said:

got the service manuel and figured out that the recitifier is for the alt/charging circuit. how does the esg work and what can i do to test it to make sure it is working correct?

Click to expand...

If you unplug the ESG you will run without it in the circuit.

You definitely could use a service manual, so you can troubleshoot the ignition in an orderly manner.

Specifications and troubleshooting techniques are in the Factory service manual, available from any dealer.

I also have a NS70A engine that I purchased last year. I still do not have it running. The boat did not have an ESG unit on it. I have replaced the CDI unit and got it to run at higher speeds but not idle. There was not a red wire running for the starter to the rectifier, so I added it a couple of weeks ago wit a 20 amp fuse in it. Could that cause the CDI unit to burn out? I have the shop manual and have checked the exciter coil (310 ohms and should be 290 ohms, Trigger coil is 22 ohms and should be 20 ohms and the lighting coil is .4 ohms and should be .34 ohms. The compression measures 120 PSI in cyl 1 and 115 in cylinder 2. I have the timing mark set right on the arrow at idle. I have cleaned the carburetors and tried opening the needles. I just purchased another CDI unit, but the measurements are the same as the other one. I also purchased a rectifier but have not put it on because the measurements are the same as the old one. I put an electric fuel pump on to see if that would make a difference. I do own an oscilloscope if there is something I can look for with that. The dealer here will not work on the engine. The kill switch wires I have tried connected and unconnected. Jim