Rectifier/Reg????

[BIG MINNOW]

Hi guys need your help on a 110 hp johnson 1986 v4 20 foot boat

Did the test ON the battery it read 12.7 start the motor let run 5 min still the same I guss I need to replace the rectifier would this also cause the motor to rev up but not move any faster when under way
This all started with the tac not working and I did replce it tac will go to0 rpm s but thats it

Thank you for all the help

 

[ezeke]

Re: Rectifier/Reg????

What rectifier do you have? If it is not working, you should disconnect it from the terminal block until you have a replacement. Be sure to map the wires so you can get them back in the right places when you have the new rectifier.

 

[SKEETR]

Re: Rectifier/Reg????

What could happen if the bad rectifier was left attached for an extended period of time, say all throughout my boats last owner.

 

[Randyg123]

Re: Rectifier/Reg????

It sounds like you checked the voltage, stated the motor and let it idle for five minutes, then shut of the engine, and checked the voltage again. If this is what you did, I wouldn't be surprise to see the battery voltage to be the same or maybe even lower.

Did you test the voltage with the motor running at a higher rpm? Test with the motor running. As the rpms increase, you should see the voltage go up (even up to 14+). This is a sign that the chargind system is working at least partially. But the rectifier could be charging but still not releasing a perfect signal for your tach to work correctly.

Check this link - http://forums.iboats.com/showthread.php?t=190638

 

[ezeke]

Re: Rectifier/Reg????

The tach defaults to zero with no signal because that is the default when the positive and negative wires are connected properly and you turn the ignition to the run position.

If the engine is on and you don't get a reading, the grey signal wire is either bad somewhere, or your rectifier is bad.

If you get no reading change on the voltmeter at the battery when changing from not running to running, then the rectifier is not working or the charging system is not working.

Bad rectifiers can allow battery voltage to run through to the stator and destroy it, which is why it is good shop practice to disconnect them when they are suspect. It is also why every troubleshooting manual tells you to disconnect them before testing the rest of the ignition system.

This problem goes back a while, see the thumbnail: