Hi,
There's a soft iron plate associated with each field coil in the generator. That's what you're polarizing (magnetically) when you go thru the procedure. They're supposed to provided enough magnetic field to produce an output voltage from the generator. That, in turn, closes the cut-out relay in the regulator, which then applies voltage to the field coils, boosting the mag field for high output.
If there is not enough magnetism in the plates you won't get enough voltage out of the generator to activate the coil in the cut-out relay.
So, you have to disconnect the power line from the generator and see if there's voltage at the output terminal with no load. If there is, then reattach the lead and measure again and see how much voltage you're losing. I'd reattach with an ammeter in the line as well (using a second meters) to see if I'm sinking current somewhere down the line.
It's also possible that the cut-out relay coil has shorted a winding or two, meaning that it will sink more current than normal and yet not produce enough mag field to close the contacts. This would be a faulty regulator, of course.
I had an issue just like this last summer. There was a piece of fuzz (looked like a weed seed of some sort) that had worked it's way into the regulator housing somehow. It was in between the cut-out relay contacts. That meant that the coil had to close with a tad more force than normal to make contact.
The symptom was that it would sometimes charge, sometimes not. When it would charge, it meant that I had to get the engine RPMs up high first. The faster the generator spins, the more voltage and current it will produce from the iron plates. Eventually, it was enough to force the cut-out relay contacts tighter and it would then 'make' and put current into the field coils. Plus, some vibration likely helped things along here.
I troubleshot it with the two-meter trick and also with a clip-cord between the battery and the field coil input terminal. That forced it to come on, but then the meters showed both a voltage and current change on the line to the cut-out, and I knew then that the issue was not in the generator, but in the regulator.
Which, was a PIA since one has to drain the coolant to remove the temp sensor from the head to then get the dash out far enough to get to the stupid regulator!
I'd have much rather worked on a bad generator!
Anyway, as I sit here reading your troubles, I wonder if you might not be fighting the same problem. You'd have a stronger mag field in the iron plates right after polarizing it. That might be enough to get it to work, but then the field will relax somewhat afterwards - so later on it doesn't work again.....
later!
Stan
