1990 Johnson 150 charging issue

[drodkey]

Looking for some guidance on trouble shooting a charging issue with my 1990 Johnson 150. Volts at the battery (dedicated starting battery) are 12.2 before starting, during idle, and at higher rpms. Reading a little that it could be the rectifier or regulator, however not finding any procedures for trouble shooting. I have ordered a repair manual but hoping to tackle the issue before it arrives. Thanks

 

[hidef]

Re: 1990 Johnson 150 charging issue

Regulator/rectifier is one unit. You can test it with a ohm meter but if you aren't seeing a voltage change it is bad. To test it with an ohm meter disconnect all wires from the regulator. Fom either yellow to the red it should be high one way and low the other way. Same with the black to yellow.

 

[drodkey]

Re: 1990 Johnson 150 charging issue

Thank you for the assistance. This site has been a huge help and resource. I've been a long time lurker but my first post. Hopefully someday to be able to return he favor someday. Dave.

 

[Haffiman]

Re: 1990 Johnson 150 charging issue

The main and most common indicator that regulator is not working is a non working tach.
Check for resistance between yellow leads from stator. Between any yellow and ground it should be 'open', no resistance/contact. If ok, replace regulator.

 

[drodkey]

Re: 1990 Johnson 150 charging issue

Made it back out to the boat today and my tach is not working. Was able to follow the wires up and it appears I need to remove the fly wheel to get to it? Any suggestions or cautions for removing the fly wheel to replace the regulator?

 

[Haffiman]

Re: 1990 Johnson 150 charging issue

Get a proper flywheel puller from NAPA or other source. Would strongly recommend to invest in an OEM workshop manual as well for your engine.

 

[drodkey]

Re: 1990 Johnson 150 charging issue

Thanks again for the advice. I have ordered a factory repair manual for my motor but was hoping to address this before it arrives.

 

[emdsapmgr]

Re: 1990 Johnson 150 charging issue

Likely the combination regulator/rectfier. There were two distinctly different regulator/rectifiers used that year. The 35 amp alternator (with the vented flywheel) uses part number 395204. The smaller 3/10 amp alternator supercedes up to 585195. Make sure you get the correct one. The 35 amp version is nearly triple the cost of the basic version.