1977 Johnson V4 140HP overcharging problem

[aok47]

Hi,<br /><br />I was out on the water at 4000RPM when i noticed the dash voltmeter reading steadily increasing to just past 14V. Then it dropped down to 12V and the tachometer also stopped working eventhough i had not changed power setting.<br /><br />Does anyone have any suggestions? <br /><br />Appreciate your help<br /><br />Angelo

 

[DJ]

Re: 1977 Johnson V4 140HP overcharging problem

That is an unregulated system. Over 14V is quite normal.<br /><br />You should check for charging with a hand held voltmeter. If it is no longer charging (the tach is a hint) you may have lost your rectifier.<br /><br />Not expensive and easy to fix.

 

[aok47]

Re: 1977 Johnson V4 140HP overcharging problem

Hi DJ,<br /><br />The rectifier has been checked and was found to be working fine, that is what has got me stumped....<br /><br />any more suggestions?<br /><br />cheers<br /><br />Angelo

 

[ob]

Re: 1977 Johnson V4 140HP overcharging problem

Stator charge coils may have failed.You'll need to perform a test and insure that they are charging.I'M wondering how you checkd the rectifier to be good if your engines volt meter is charging at 12 volts.Did you verify voltage at battery while running engine?

 

[DJ]

Re: 1977 Johnson V4 140HP overcharging problem

That's why I suggested checking the charging system with a handheld volt meter.

 

[aok47]

Re: 1977 Johnson V4 140HP overcharging problem

I checked the rectifier with the engine not running. I havent verified the voltage at battery while running engine. I have been relying on the dashmounted voltemeter.<br /><br />so i guess the next step is to check the voltage at the battery whilst the engine is running.<br /><br />At constant RPM would you expect the voltage to rise? i would've though it should remain constant for a constant power setting... <br /><br />I'm by no means an expert in outboard so please bare with me.... <br /><br />thanks again<br /><br />Angelo

 

[DJ]

Re: 1977 Johnson V4 140HP overcharging problem

The voltage will continue to rise as the battery becomes closer to full charge.

 

[Hooty]

Re: 1977 Johnson V4 140HP overcharging problem

Check the voltage at the battery with a handheld voltmeter with the engine running at high idle and with the engine stopped. If the rectifier is okay, the voltage will be higher at the high idle.<br /><br />c/6<br />Hooty

 

[aok47]

Re: 1977 Johnson V4 140HP overcharging problem

Ok,....<br /><br />I connected my multimeter to my battery and measured the voltage whilst the engine was running at 3000RPM. The voltage gradually increased to about 14.7~15V when the tacho stopped working and the reading on the voltmeter started to drop. <br /><br />Appreciate your thoughts again,...<br /><br />Angelo

 

[Hooty]

Re: 1977 Johnson V4 140HP overcharging problem

I suppose a rectifier could work intermittently. Nothing's impossible. I think I'd start looking for a loose or corroded connection though.<br /><br />c/6<br />Hooty