And if you set this test up:


What AMPS are you reading at the external Ammeter? And if you take a volt reading between ground (+) and the ARM terminal on the generator?

 

The voltage between the generator arm terminal and ground is the same as the voltage regulator arm and ground (4.4 volts). I have not measured the amps going into the ammeter battery wire, but it is always showing a slight discharge state or more when I turn the lights on.

Thanks

 

Maybe the nuance of the test was lost, but the regulator ARM and Field terminals are disconnected, and a jumper is connected between the ARM and Field terminals of the generator. An AMP meter is also between the generator ARM and the battery (-) terminal.

 

Based on this test you have done, and you have verified with your variable voltage power supply that the cut out relay pulls in at a little over 6 volts. And then have ran test jumpers overlaying the Arm, Field and Ground wires between the regulator and the generator , I am wondering if your firewall is grounded properly. Some trucks had the battery ground connected to a welded stud on the firewall then from there a braided jumper from the firewall to an intake bolt or a bell housing bolt. Some trucks had the battery ground run directly to engine block using a mounting bolt on the coil bracket. Brian I bet could tell us how his trucks battery systems are grounded. Just my opinion here but since the starter demands the most current its good to run your battery ground strap right to the engine block but then due to rubber cab and engine mounts, its also important to add a dedicated ground from the block to your firewall then another from the block to frame. That way your engine block is your main ground reference point.

Anyway after all that, where is your battery ground strap connecting to, and from that point could you add a test ground jumper between there and the voltage regulator base?

Hang in there. You're going to fix this truck!

Hoping you have a Great Easter by the way.

 

Thanks for hanging through this with me, appreciate the patience.

as far as I can tell is only have a ground from the battery to the engine block. While I agree another ground to the firewall would help I’ve already ran a jumper from the battery ground directly to the voltage regulator base with no change.

 

so jumping the field and arm terminal on the generator does not yield anything. I had the Amp clamp on the ground cable. Oddly enough I can only get it to full field charge when the regulator is hooked up normally and the generator arm to field jumper is installed.

thanks

 

So you didn't perform the test as prescribed?

 

Apparently not, but I just did after re reading everything and it charges at 8 plus volts and 30ish amps.

thanks

 

Thanks! Sorry if it seems we are being pedantic, but details matter because so far it seems the generator and regulator individually test okay thus far and the overlays kinda rule out the wiring. I'll need some time to review and think through this. Maybe something is jumping out to someone else...

It may be obviously redundant, but just to be clear, this is a 6V positive ground (⏚), and so when we say ground, we mean a connection to the (+) size of the battery, and by power, we mean the (-) side of the battery which is reverse of what some consider conventional.

 

I absolutely appreciate the effort, and agree details matter. Yes this is a positive ground system. In the last test the armature was jumped directly to the negative terminal.

thanks

 

So it sounds like you completed the first test Brian mentioned. Now lets have you do the second test. The Open Field Circuit test. Engine not running, you basically remove the field wire from the generator, connect a test lead that runs from the gens field terminal (you dont see any greenish corrosion around that terminal do you?) thru your amp clamp, and connect the other end to your battery neg terminal. You should read some current here, maybe 3 amps, whatever it says in your Service Manuals generator testing section.
I was re-reading through this whole post today and I missed the part where you said your generator wouldn't really motor test. Maybe weak field windings? The Open field test will give us more information about that. It might explain why the generator seems to have too low of voltage to pull in the cut out relay.

 

I went through the same thing. The breaking point was after a nice dinner out with my wife, my truck didn’t have enough battery charge to start. I enlisted some help and push started, but the last 100 yards or so of my 8 mile drive home it wanted to quit with headlights on.

My fix was to replace the generator with a PowerGen 6v + ground alternator. It looks just like the stock generator and doesn’t need a regulator. I left the regulator in place for appearance, then when our friend hooler1 was having trouble at Truckstock, I gave it to him. It didn’t fix his problem right away, but I hope he was able to fix his charging issue.

https://www.jegs.com/i/Powermaster/7...BoCDS8QAvD_BwE

 

I'm hitting the limit and ready to go with an alternator as well. What setup did you use? My flathead is operating 12v negative ground. When I test the generator it flashes between different voltages.

 

Jumping from the field of the generator to the negative shows 3.3 amps.

thanks

 

Well, it sounds like your field tests good then, not open nor shorted. And obiviously if you can get some 30 amps out of your generator shorting the Field to Armature it looks like your generator is good. I am still trying to figure out why its only sourcing 4.4 volts to your voltage regulator. Is the 4.4 volts at idle or when your running the RPM upto around 1500?