89 Evinrude 90VRO starts charging when testing with meter???

[rbraden4]

I recently noticed my 89 Evinrude 90 wasn’t charging so I started looking into it. The Tach works fine, battery is new, but here’s the catch while the motor is running I take my volt meter to test the wires at the terminal strip and as soon as I touch the test lead to the purple wire the motor starts charging at 14.3v and continues until I shut the motor off.
once I start it back up, same thing won’t charge until I test that purple wire again. When testing I’ve got one lead on the block and the other lead to the purple wire.
this one has me stumped...

 

[racerone]

------What does voltage show on the BATTERY with motor stopped.-----What does battery voltage show when motor is running at a fast idle.

 

[rbraden4]

------What does voltage show on the BATTERY with motor stopped.-----What does battery voltage show when motor is running at a fast idle.

About 12.2 engine off about the same at idle, I’ve seen it move up as high as 12.6 at about 2500 rpm but just up on high idle it’s sitting at 12.2-12.3

 

[Tim Frank]

Make sure all ground connections are clean.

 

[jakedaawg]

You have a bad, loose, dirty, or corroded ground wire or connection.

 

[oldboat1]

^^Include battery cables (sandpaper ends until bright). You might also clean up the screws and bridge on the terminal strip, and reattach. Simply loosening screws and spraying with electrical cleaner, then reattaching, might make a difference.

 

[rbraden4]

I ohm’d our the grounds and they were good but I will clean them up and re check

 

[flyingscott]

Why are you testing the purple wire? Most of those regulators have 2 yellows 1 red 1 gray and 1 purple wire. Purple is the accessory wire and VRO and Grey is the tach wire. The 2 yellows are AC wires from the stator. The red wire should be connected to the positive cable at the solenoid and that is your charging wire.

 

[rbraden4]

Why are you testing the purple wire? Most of those regulators have 2 yellows 1 red 1 gray and 1 purple wire. Purple is the accessory wire and VRO and Grey is the tach wire. The 2 yellows are AC wires from the stator. The red wire should be connected to the positive cable at the solenoid and that is your charging wire.

Just going off a chart I saw, that stated purple should have battery voltage, so I checked red, and when I checked purple I saw the battery gauge shoot up.

 

[Vic.S]

Just going off a chart I saw, that stated purple should have battery voltage, so I checked red, and when I checked purple I saw the battery gauge shoot up.

The purple wire is a sensing wire , it should have the battery volts on it when the engine is running, being energised via the accessories terminal on the ignition switch
Many more modern and replacement regulators do not have a purple wire because the sensing is done internally. Service bulletin 2001-01(P) refers to this

The purple wire should be connected to a point which becomes energised to battery volts when the key switch/ ignition switch is in the on, or run, position.

However I do not understand why your regulator turns on when you touch the purple wire with a volt meter.
Do you see battery volts on the purple wire when the ignition switch is on?
Perhaps you should check your ignition switch to ensure that the accessories terminal is energised when in the on position

 

[rbraden4]

The purple wire is a sensing wire , it should have the battery volts on it when the engine is running, being energised via the accessories terminal on the ignition switch
Many more modern and replacement regulators do not have a purple wire because the sensing is done internally. Service bulletin 2001-01(P) refers to this

The purple wire should be connected to a point which becomes energised to battery volts when the key switch/ ignition switch is in the on, or run, position.

However I do not understand why your regulator turns on when you touch the purple wire with a volt meter.
Do you see battery volts on the purple wire when the ignition switch is on?
Perhaps you should check your ignition switch to ensure that the accessories terminal is energised when in the on position

Yes, using a digital test light it reads battery voltage only when the key is on and as soon as I start the motor voltage goes up to 13.8-14v same situation but without the test light on purple I start the motor and watching the bolt gauge in the dash voltage is only 12.3ish I head back to the motor watch the gauge and touch the test light and as soon as I touch it the voltage starts heading up again and it will continue to charge till I shut it off. That’s what has been going on. Today I cleaned all the grounds, cleaned all the terminals at the battery gauge and once done I fired the motor up raised the idle to about 1300 rpm and slowly the gauge started going up to 14v so I can’t say what it was for sure but it must have been a connection somewhere. As of today it seems to be working fine, I will have it out on the lake this weekend and keep an eye on it.

 

[Vic.S]

Yes, using a digital test light it reads battery voltage only when the key is on and as soon as I start the motor voltage goes up to 13.8-14v same situation but without the test light on purple I start the motor and watching the bolt gauge in the dash voltage is only 12.3ish I head back to the motor watch the gauge and touch the test light and as soon as I touch it the voltage starts heading up again and it will continue to charge till I shut it off. That’s what has been going on. Today I cleaned all the grounds, cleaned all the terminals at the battery gauge and once done I fired the motor up raised the idle to about 1300 rpm and slowly the gauge started going up to 14v so I can’t say what it was for sure but it must have been a connection somewhere. As of today it seems to be working fine, I will have it out on the lake this weekend and keep an eye on it.

Thanks for the feed back. Hopefully cleaning the ground connections has sorted it. I still cannot understand or explain what was going on though!

 

[jakedaawg]

Thanks for the feed back. Hopefully cleaning the ground connections has sorted it. I still cannot understand or explain what was going on though!

The meter was acting as a ground in a sense...it allowed the regulator to know to produce or route if you will, charging voltages. Same scenario as when you think you have a bad starter solenoid, put your meter on it to confirm and it is suddenly working, it always turns out to be a faulty ground.

 

[oldboat1]

^^Hard to sell this, somehow. The meters come out until it's back to basics out of frustration, confusion, and/or as a last resort.

 

[jakedaawg]

True story, right hand. The meter completes the circuit. Verified by the fact he cleaned the grounds and it worked as I suggested early in the thread. I'm just no good at explaining.

 

[cfauvel]

The meter was acting as a ground in a sense...it allowed the regulator to know to produce or route if you will, charging voltages. Same scenario as when you think you have a bad starter solenoid, put your meter on it to confirm and it is suddenly working, it always turns out to be a faulty ground.

Well that's one for the archives and memory banks. Cool