Recently I posted about a pulsating ammeter gauge, which occured just after my HEI install. A new voltage regulator had no effect, but as mentioned, the gauge settled down a bit, and I decided not to worry about it.

Today I took the car out, and within a few seconds of getting on the road, the ammeter pegged to full charge-and stayed there!! When idling out of gear, the gauge goes back to center. Put in gear, with the brakes on at idle and the gauge dips to almost full discharge. Then at any rpm above idle, the gauge goes full charge again. It's almost like there is no voltage regulator present!

One interesting thing; at idle the battery shows about 13 to 14 volts. When revved up with the gauge showing full charge, the battery still shows 13 to 14 volts. Also, turn the key on but don't start the engine, and the gauge shows a discharge. The battery is strong and shows no slowdown in cranking.

Am at a real loss here guys. Any opinions? Thanks!
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TX311M

Tell us about the regulator ground.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have a ground wire coming off one of the regulator mounting bolts going to the mounting plate of the HEI (which itself is grounded to the body and batt) and from there to the battery terminal. There is also the ground wire from the body to the block (not to mention the ground wire from the batt to the block). Even if the body were somehow not grounded, the VR case is grounded to the batt and block. I've checked for continuity between the case of the regulator, the battery terminal, the body, and the engine block in all possible combinations and get complete continuity. Can't find a ground problem.

Now, I'm not great at electronics althought I understand the theory. Couple of things I'm not sure about... My alternator has two field wires, as I guess most post '72 or so do. If I had accidentially reconnected the two field wires backward, or if one of the wires has broken somewhere (maybe inside-can't see anything outside), could this be the problem?

I had also planned to change out the alternator brushes in case they were worn, but I can't see that causing this problem. This wasn't a gradual thing. Yesterday the amp gauge was okay if somewhat still jittery. Today, well...like I said, it's suddenly as if there were no voltage regulator.

I suppose it's possible that the new VR simply died, but it's only a few days old!
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easy vape

Doesn't sound like there's anything the matter with your grounding.

It doesn't matter which way the two field wires are connected to the two field terminals.

If there's an internal fault in the alternator grounding one of the fields, you'll get this behaviour you describe. Try pulling one, then the other, then both of the field wires off and seeing what happens with the ammeter when you start the car.

At this point I'm looking askance at the alternator. What's its history?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'll try pulling the field wires off as you suggest in the morning and report back. The alternator was on the car when I got it about a year ago. Looks like a plain old stock alt for that year. Never had any trouble with it. However, I did pull it to change the engine timing chain just before doing the HEI swap, which is why I asked about possible crossed wires. I had thought about changing the brushes (and still probably will) when it was suggested that worn out brushes might be the cause of the jittery ammeter, but I don't think it is causing this latest problem...might be.

By the way, I thought (probably wrongly) that one of the fields was supposed to be grounded. No? Should I check each field connection to see if it's grounded to the alt body?
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vapormatic vaporizer

If you are putting a late alternator into a car with the early VR/charging configuration, then one of the two field connections is grounded off.

-D.idiot

Process of elimination, first thing I would do is pull the alternator and have it tested-fairly easy to take out, and any kragen etc. will test it for free.

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<img src="http://farm4.static.flickr.com/3173/2992308402_5481afb26e_t.jpg">

Okay Dan, I tried pulling each, then both, field wires off and starting the car. Before I tell the results I should mention that a buddy traded me for a new (rebuilt-and yes, tested at Kragen's) alternator last night which I installed this morning, along with a brand new VR. I also checked the wiring everywhere, finding a melted terminal at a multi-connector (not a bulkhead connector) where the heavy hot wire from the alternator connects. I bypassed it with a good, solid soldered crimp. I don't see any damage or corrosion at the bulkhead connector. The results of these parts swaps and rewiring were...nothing! The ammeter still ticks (almost looks like a pulse) high maybe twice a second in idle. It does now, however, smooth out in higher rpms. The new VR did however stop the high charge rate....so far, although it does charge high for the first 10 or 20 seconds after just starting. But it was doing this jittering before the last VR went out, so I'm still worried about it. The problem seems to be mostly at idle or lower rpm's now.

Oh yea, another thing I noticed this evening is that the lights, all of them headlights included, pulse along in time with the ammeter. I know that pulsing headlights at idle has been a problem with older Mopars, but I never had it before this started.

Although this started at the time of the HEI install, since the module and coil are connected directly to the battery plus terminal through a relay, I can't see it being a factor in this problem, but rather just a coincedance....or?

Okay, just now after that work, I pulled the field wires. With either one (but only one) of the green or blue field wires pulled loose (from the alternator), the ammeter is dead still at center. No rpm changes this. It just doesn't move at all. With both wires pulled the same thing, but it centers slightly more on the discharge side. I forgot to put a load (lights, etc.) to it to see what effect that would have, but at idle and and higher rpm it shows absolutely no charge or discharge. Put the field wires back on and the gauge responds, but the pulsing starts again.

What does that tell us? Thanks!
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Yamaha RBX6JM

i would try hooking an amp clamp around your alternator output wire and compare that reading to your gauge.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

Zero ammeter activity with field wire(s) pulled tells us no grossly weird shorts in the alternator (it was a long shot anyhow).

I'm still looking askance at your alternator — now also at the wiring to the voltage regulator, and between the regulator and the alternator.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I checked the wiring to the VR. The green wire from one field to the VR has good solid continuity and no shorts to ground. The other VR wire goes to the power feed (actually goes to one side of the resistor block wiring) and it too is fine.

In the last few days (starting after I swapped in a new VR) it has calmed down a bit. The pulsing is still there, but only bad at idle. As rpm's climb the pulsing increases in rapidness but goes down in intensity until, at rpm's about 2500 and above it appears to be gone.

Here's another strange thing. At idle the engine changes rpm slightly (hunts up and down slightly over a range of maybe 50 rpm's) which it never did before...and, the ammeter pulses in sync with it! The engine and carb were well tuned before this without this effect.

Now, an admission: I did the HEI conversion using a Wells module. Yea, I know they are not the best, and I'm wondering if some fault in the module might be causing a pulsing draw of power? Just after starting the engine there is also heavy charging for maybe 10-20 seconds.

As mentioned, it now has a rebuilt and tested good (I didn't see the test!) alternator in it, so I plan to take a closer look at the multi and bulkhead connectors.
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Suzuki GSX-R Series history

The pulsing makes my think of a bad diode in the alternator......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Continuity, schmontinuity Remember, a continuity meter does not load the circuit. The current it passes is tiny and can't tell you how the circuit behaves under actual, real load. I still think you've got dodgy charging system control wiring.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Allright, I can rewire the leads from the VR without much of a problem. What other wires should I check? As I mentioned, I found the hot wire from the alternator went to a multipin connector (not a bulkhead connector) and the connector was melted at that wires pins. Fixed that, but what other wires besides the VR wires should I consider?

A number of people have mentioned a bad diode in the alternator. I have mounted a new (rebuilt) one that supposedly checked good (I didn't see the test) but I suppose it's possible it could still be bad (wouldn't be the first time). How difficult is it to get at the diodes in these 2 field alternators, and what are the symptoms of a bad diode? It seems to me that if a diode was causing the ammeter pulsing, it would be fast, even at idle, to the point that the ammeter needle would be moving in a blure. But at idle the pulsing is sharp, and happens maybe 2, sometimes 3 times a second. Still seem possible?

By the way, I understand if you all are getting tired of this particular topic, but I'm just trying to get it fixed.
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Mazda 757 history

I agree with you that the pulsing as described is too slow to be due to a faulty diode. Assuming the "remanufactured" alternator is any good — admittedly a pretty big assumption — I really think you've got a classic feedback loop here. Voltage regulator isn't seeing true line voltage, it's seeing something less than line voltage, so it throws more coal on the fire, which causes line voltage to spike, now even the "half blind" voltage regulator thinks the line voltage is a little too high (actually it's a lot too high) and reduces power to the field, which drops line voltage to normal, but the regulator sees it as too low, so throws more power to the field...lather, rinse, repeat.

I would not just put in new wires same as the old wires; I'd mock-up the charging circuit with wires directly from a known-clean line voltage takeoff point (alternator B+ or battery positive), bypassing all the factory connection points, switches, pass-throughs, etc. and of course ensuring good clean grounds, including regulator base ground...if you can make the system work well that way, then it's simply a matter of laying in a new circuit with the necessary switches and pass-throughs, etc.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.