Replaced Alternator- Now Someting's F#$@ed Up!...help!

[scouthead]

I replaced my alternator today to try again to get my ammeter to stop tweaking out. After putting in the new alternator, the meter bounced even more violently at Idle, would stay right in the middle while driving(acces. off) and would sweep up to the top and jump back down to the middle every time I reved it up. Voltage at battery between 13 and 15.25 depending on rpm...THen while checking voltage at battery at higher rpm with some things turned on, something happened.
Now every time I start it, it runs like S%$# for about 5 seconds and blows the engine fuse. I have two voltage regulaters, both were working before, and one was new. swapping between them makes no difference. I have checked the resistance in both the alternator and regulaters according to the factory manuals, and everything seems to be right. I checked the fusible link and it seems O.K.
I don't know where to go from here, and I'm getting really pissed off...
If anybody has any Ideas or suggestions I'd appreciate the help.
'76 FJ55 with all stock running gear and low miles 2f. Ran like new yesterday-just the stupid ammeter bouncing and lights flickering along with it.

 

[spotcruiser]

Check your idle solenoid. Sounds like you had a faulty voltage regulator. Also sounds like your idle solenoid may have shorted, perhaps as a result of the faulty regulator.

 

[Pin_Head]

There are only 3 things on the engine fuse: voltage regulator, idle fuel solenoid and smog computer, so you can figure out which is the problem by disconnecting them and reconnecting one at a time.

A flickering amp meter needle and lights isn't that unusual with a machanical voltage regulator. If it swings wildly, it may be due to a bad connection in the chassis power feed wire to the amp meter and from the anternator all the way to the fuse block and voltage regulator. It can also be a bad ground at the VR or a missing ground wire (white/black stripe) between the VR and alternator.

Was the replacement alternator new or tested good? It might have an intermittent short.

If you only had a volt meter it wouldn't be as obvious that the current is surging because the needle would only flicker between 12 and 14V.

 

[scouthead]

Thanks guys, I thought about the Idle solinoid, but dismissed it as it would idle for a few seconds after replacing fuse...I'm gonna check it out. Also gonna swap the old alternator back in right now and see if it will work like before or not...jeeze it's freeezing outside right now...

 

[scouthead]

forgot to tell you that the alternator was a rebuild, and that when I pop a new fuse in it now, and start it, the ammeter goes all the way down to the bottom like there's a massive drain, and then after a couple seconds, slowly comes up to the middle. That's when the fuse blows and it stops running.

 

[scouthead]

reinstalled old alternator and stopped blowing fuses...now ammeter seems to be working better than it ever has...hmmm... never known anything like this to fix itself...W.T.F.!!??

 

[MrMoMo]

Sounds like your "new" alternator has a short in it. Is it possible that you are installing the output wire on the wrong post? - it should be an insulated post.

 

[scouthead]

no, everything was connected properly, just not working...took alt. back...no questions asked...must get a lot of them returned. I'll try one from someone else next time.