1968 Johnson charging system

[aaromba]

I need help to figure out if my motor's charging system is working. And how do I troubleshoot?? Its a 1968 55 HP model TLR-10R. Thanks for everyones help on the shifting problems. Its up and running great except for this on last thing!!! Don't figure.

 

[Vic.S]

Re: 1968 Johnson charging system

The first thing to do is check the volts at the battery (best to start with a battery that you have charged probably) which should be 12.7 or thereabouts if it is charged then start the motor and recheck the volts at running revs. The volts should rise above the original figure and the battery will be charging once they reach 13.6 - 13.8 or thereabouts.

You can check the rectifier as described in the post on checking rectifiers on the "Engine FAQs" forum but if you are using a digital multimeter use it on the diode check range.

You can also check the output from the coils with a meter on AC volts and/or do a continuity check on them,

 

[aaromba]

Re: 1968 Johnson charging system

Thaks Vic I will try that

 

[aaromba]

Re: 1968 Johnson charging system

Thanks!! I checked out the rectifier and that is the problem!!! Thanks again

 

[Vic.S]

Re: 1968 Johnson charging system

I checked out the rectifier and that is the problem

I suspect rectifiers fail because people accidentally connect the batteries the wrong way round. Even for a second it's instant death to a rectifier.

Disconnecting the battery while the engine is running could be a cause as well. It certainly is to the diodes in an alternator in a car or inboard engine. Again instant death.