Voltage Regulator or Stator

[RPHodge]

Motor: 92 Mariner 60hp 3 cyl 2 stroke s/n OD 0183347

Problem: Motor will start and run fine only when the voltage regulator is disconnected. Once running, attaching the 2 red leads from the solenoid (each reads 12.5 V DC output) to the voltage regulator causes no change and motor continues to run fine. Attaching the grey tach line of the voltage regulator causes no change and motor continues to run fine. Attaching either of the 2 yellow stator leads (each read -2V AC output) to the voltage regulator causes the engine to die immediately.

One opinion says that if the engine is starting and running fine (without the voltage regulator attached) then the problem is not due to a bad stator.

I've changed out the voltage regulator and no change, same symptom.

What's going on? Did I get a bad voltage regulator? I did the ohms tests and both the old and new Volt Regs gave almost exact readings. Either both are good, or both are bad, or I have a different problem.

I checked for shorts and grounded cables and found nothing obvious in the wiring. The battery is good, clean terminals, 12.5 v and good cables.

The stator was just replaced 6 months ago (an outboard mechanic friend says it's not the stator). The motor starts and runs fine (on water muffs) without a voltage regulator, won't start when the voltage regulator is connected.

All I can figure is that something with the stator charging circuit is not right (-2V AC?). Why would the engine immediately die as soon as one of the yellow stator leads (either one) touches a voltage regulator yellow connector? Another bad regulator? Or is it really the stator?

Help! Any outboard electricians?

 

[j_martin]

Re: Voltage Regulator or Stator

Motor: 92 Mariner 60hp 3 cyl 2 stroke s/n OD 0183347

Problem: Motor will start and run fine only when the voltage regulator is disconnected. Once running, attaching the 2 red leads from the solenoid (each reads 12.5 V DC output) to the voltage regulator causes no change and motor continues to run fine. Attaching the grey tach line of the voltage regulator causes no change and motor continues to run fine. Attaching either of the 2 yellow stator leads (each read -2V AC output) to the voltage regulator causes the engine to die immediately.

One opinion says that if the engine is starting and running fine (without the voltage regulator attached) then the problem is not due to a bad stator.

I've changed out the voltage regulator and no change, same symptom.

What's going on? Did I get a bad voltage regulator? I did the ohms tests and both the old and new Volt Regs gave almost exact readings. Either both are good, or both are bad, or I have a different problem.

I checked for shorts and grounded cables and found nothing obvious in the wiring. The battery is good, clean terminals, 12.5 v and good cables.

The stator was just replaced 6 months ago (an outboard mechanic friend says it's not the stator). The motor starts and runs fine (on water muffs) without a voltage regulator, won't start when the voltage regulator is connected.

All I can figure is that something with the stator charging circuit is not right (-2V AC?). Why would the engine immediately die as soon as one of the yellow stator leads (either one) touches a voltage regulator yellow connector? Another bad regulator? Or is it really the stator?

Help! Any outboard electricians?

The stator has 2 sets of windings on it. One feeds the voltage regulator. The other feeds the ignition system. They should be totally independent of each other. You should be able to totally short out the voltage regulator and not kill the engine.

Check for continuity between either of the yellow wires and all the other wires from the stator. There should be none except to the other yellow wire. If there is any, the stator is bad.

If that's good, check the stator output to the ignition with a DVA. I would bet it drops drastically when you connect the voltage regulator. It shouldn't. If it does, pull the flywheel and take a look for loose magnets, or contact between the flywheel and the stator. Thought is a bad flex plate or upper main bearing allowing the flywheel to contact the stator when a little pressure is put on it by loading the alternator coil, causing a magnetic short.

The 2v AC output to ground from each yellow wire is of no significance. It would just indicate you have a sensitive meter. The voltage between them should be about 15V at idle, up to 90V at WOT. It does indicate that there is probably no electrical interconnection between the coils. (as it should be) as one would expect the readings to ground to be different, and at least one significantly higher if there were an internal short.

In any case, the trouble is under the flywheel.

hope it helps
John

 

[Faztbullet]

Re: Voltage Regulator or Stator

My vote is stator....

 

[RPHodge]

Re: Voltage Regulator or Stator

Thanks guys!

I'll get under the flywheel and check the stator out after I get the right tools together for that job.

This stator is only 6 months old, but it could have fried the day the engine overheated, when the problem first arose (likely due to dying water pump, fixed now).

 

[sschefer]

Re: Voltage Regulator or Stator

I agree it's a stator problem but due to the overheat condition you might get lucky and find the two yellow leads are melted and there's bare wire touching the stator frame. It's worth checking and might be repairable. Just a thought that might save you a couple of Benji's.

 

[RPHodge]

Re: Voltage Regulator or Stator

I've looked at the stator wires and from what I can see they all look intact, none are scorched, melted or shorted. This is the black stator design
(5 leads: Blue, Red, Black and 2 Yellows), so I can only see up to where they come out of the stator. I haven't a flywheel puller (yet), so I'll check for severe rubs or melts on the stator magnets once I get the flywheel off.

I did check the stator leads for continuity as John suggested. Yellow to Yellow was normal for continuity (1.5 ohms on RX1 scale). Any Yellow to any other lead (Blue, Red, or Black) showed no continuity (around 50,000k ohms). So this all seems normal.

Will let you know how the magnets look on the stator once I've pulled the flywheel.

Still baffled why this apparently good voltage regulator seems to short out and kill a fine running engine when attaching it to any stator Yellow.

 

[j_martin]

Re: Voltage Regulator or Stator

Have you ever heard a transformer buzz when a lamination gets loose. Same thing can happen in a stator. The bus is because there's mechanical force being put on the various parts, so it could ohm out perfectly normal, and then get a short, or arc over as it runs if anything is loose internally. Doesn't happen often, but it happens. It's possible that loading the battery charging coil makes it move a bit internally and contact something it shouldn't.

That's why a DVA is so durned important.

 

[Faztbullet]

Re: Voltage Regulator or Stator

I did check the stator leads for continuity as John suggested. Yellow to Yellow was normal for continuity (1.5 ohms on RX1 scale

To high should read 0.16 - 0.19
DC Resistance of these windings generally is less than
1.5 Ohms. If a reading resembling a short is obtained, this
would be acceptable.

 

[RPHodge]

Re: Voltage Regulator or Stator

OK, so I've got the flywheel off and no visible damage or signs of why the stator yellow leads are shorting out and killing the motor when I attach it to the new volatage regulator. The stator is the old Mercury kind that is heavily insulated in black rubber and I suspect that something is wrong inside but I can't tell from looking at the surface. I'm still looking for a reasonable DVA but I've also gone ahead and ordered a newer type CDI stator (not insulated). I have read on another post here that the insulated ones tend to overheat and go bad often (a Mercury problem). I'm in Texas and this might explain why in two years in a row I've burned up two stators (one new) in mid summer. I've only had this motor two years, but I run it almost every weekend til the problems.

I feel like I'm chasing parts and tools here, but eventually this motor will run right again.

 

[roncoop75]

Re: Voltage Regulator or Stator

I'm still looking for a reasonable DVA

Build one. Instructions are in the electrical forum. I think I spent $15 but I put it in a box and bought some nice leads. I could have done it ugly for $5.

 

[RPHodge]

Re: Voltage Regulator or Stator

Well it turned out to be a bad stator after all!

I replaced it with the newer uninsulated CDI stator and it runs like a top! Ran the motor on the water all Labor Day weekend. Started on the first try each and everytime and never stalled once. Smooth at WOT 5500rpm and for a 2 stroke it's very quiet.

Even though the old stator looks ok I will probably find something shorted if I strip off the heavy black insulation. I'll not use these type again. Too hot for Texas summers.

Finally got a DVA in the mail. Found one for $30 from patriot.electronics . It looks homemade but works great. Wished I had it a month ago.

So alot of repairs and replacements were accomplished in the last month and here in Texas we still have a lot of good summer weather to run on the water.

Thanks to all who responded!