Volt gauge drops to 0, but engine cranks and starts

[TheCrazySwede]

Thanks a lot guys! You are all a great! Really appreciate the help

I'll feed some more background into the situation.

I recently went from an EFI L28 to a carbed L28

Only thing new, electronically, is an electronic fuel pump.

Since engine swap, I noticed my volt gauge would read past 16v. I thought maybe my regulator was bad or maybe alt. I replaced alternator with new internal regulated version. I jumped the cable that connected to the external regulator, as instructed on Atlantic Z. (Boy, that website is amazing!)

Since, I've noticed my alternator has still had issues where it outputs a lot of juice and burns my fusible link. The link that keeps burning is the one that goes from the alt and to the battery. Looking at the wiring diagram, it also connects into the voltage regulator (the old external one that now has its connections jumped.)

Another thing to note is that this issue I'm experiencing now is not new. I was having similar issues with the old alternator, too. And with the new one - but the issues sort of went away on their own. 

I'm thinking maybe there's a ground wire somewhere that isn't hooked up properly. When I did the motor swap. Or maybe my fuel pump hookup is jacked - who knows.

I'm going to do some back-tracking to try and find the sucker causing this issue, since I had no electronic issues prior to swapping my motor. Funny how I went from an electronically motored engine to a fully mechanical one and ended up with electronic issues, haha

 

[Zed Head]

11 hours ago, TheCrazySwede said:

 I noticed my volt gauge would read past 16v.

Since, I've noticed my alternator has still had issues where it outputs a lot of juice and burns my fusible link. The link that keeps burning is the one that goes from the alt and to the battery. Looking at the wiring diagram, it also connects into the voltage regulator (the old external one that now has its connections jumped.)

Another thing to note is that this issue I'm experiencing now is not new. I was having similar issues with the old alternator, too. And with the new one - but the issues sort of went away on their own. 

Does the meter still show 16+ volts?  You might not have the S wire connected properly.  Maybe that is damaging the alternator's regulator, or passing too much current, although that should damage more than the just the fusible link,  The link is designated for quite a bit of current.

You can check both S and L at the alternator with the the T plug disconnected.  They should both show battery voltage with the key On.  I would do that first.

[beermanpete]

It sounds like you might have two (or more) problems. Assuming that it all started when you did the engine/carb swap, start by looking for cut or pinched wires, unhooked ground between the body and the engine, etc. The first issue, voltmeter reading falling when turning on the electrical accessories, is likely a poor connection somewhere. Just good enough to power the volt meter but has a large resistance and therefore a large voltage drop with any real load. The second issue, blowing the fusible link at the alternator output, could be due to a bad alternator/regulator or a missing voltage sense at the S-terminal (as Zed Head already mentioned). Try letting the car run but don't race the engine. When the engine is at idle the alternator output won't be enough to blow the link and you will have time to perform tests.