Mine is a 95 TA. Different then what you are showing and they are circuit breakers. I bought a new one anyway but my old one does have continuity so I think it is OK.

 

I've put jumper cables on. Pos. on the pos. terminal on the battery to back of alternator and neg. on negative terminal of battery to alternator case. This should test the "too small gauge wire" theory. Nothing changed when I did this.

I just go back this evening and will mess around tomorrow.

 

Does this excerpt fit the description of the Lonnie's dual fuel system you have in your car? :

"Under normal conditions, only 1 pump runs, so there is no additional load on the charging system, nor is there any fuel heating associated with these kits as commonly found with high flow single race pumps. Now you can enjoy your car, driving it cross country if desired, just as if it had the stock pump.

When the fuel demand increases, the second pump engages to allow ample fuel for severe power demands. This second pump is either enabled based on boost, nitrous activation, or via an RPM switch (sold separately) for normally aspirated engines.

These kits are equipped with a plug-n-play wiring harness to make the install as easy as possible, utilizing original equipment quality relays & weatherpack connectors. Internal fuel lines are OE style corrugated nylon."

 

Are there any electronics that are connected directly to the post of the alternator?

If so, try moving them off the alternator post and get them on the + battery post....then see if it fixes the problems. Have only the OEM charging cable to the battery on that alternator post.

I've got to look at a couple of things in the factory manual to refresh my memory on the alternator schematics.

 

Yeah, that pretty much is it. The main pump is on all the time and the second one comes on with boost via a hobbs switch. I am going to check fuel pressure today. I suspect it is a bit higher but shouldn't cause the car to barely run. The PCM should be able to deal with a little higher fuel pressure.

 

No. The two fuel pumps are on the positive post of the battery and a ton of stuff on the positive distribution block.
I am going to dig for inline fuses for the fuel system, ignition box, electric water pump, whatever I can find.

 

Fuel pressure is 45psi. Before or with dead alternator when running good it was 41psi.

I added 25% to injector size. No change. Still ****. I tried keeping my foot on the throttle instead of bliping (where I saw no change in RPM to throttle input) and the motor died. Flooded out no doubt.

A little backstory:
Fall 2015- I forgot to put a plug boot on and went to to put the car in the garage. It hard started for the first time in years for obvious reasons. Put the boot on and all was good.
A few weeks later every time I started the car it was a real hard start. Sometimes up to 3 tries. It did this for the rest of 2015.
2016- I work on other things on car which took till Sept. Car hard starts again. Do the no start check list to find out a shop bypassed my ignition box (for 5 years!!). It starts then the alternator gremlin popped up. I took it for a drive and found the alternator not to be working. Got new alternator and tested with known good alternator. In my rush to fix it I started it again without a plug in a cylinder. I run out of time to work on the car and it goes to sleep
2017- It won't start. I did the no start checklist and it turns out I killed the coil. It seems having an open plug wire boot arcing can overtax the coil and kill it. Then I start working on the alternator problem again.

I wonder if all this sparking might have torched something else? But why would it be AOK with no alternator? Electrical gremlins are the worst!

 

How stable is the excite wire voltage wise?

 

It's all over the place like the alternator voltage. Mid 13Vsd and jumping. I'll look again.

With the bad alternator/runs good the exciter wire is 1.09V.

I've read there is a resistor between the exciter wire connection on the alternator and the gauges. Not sure where in the harness or what it looks like.

 

There should be.

Quick test would be to run a line from battery hot into a 470 omhn resistor then to alternator. For the excite wire.

 

As far as I know the exciter wire goes from the alternator to resistor to gauge cluster. I'll look into it.

 

It does. To a switched 12v hot source. So bypass that was what I was saying.

 

Here is the troubleshooting chart for the charging system(1996).

Were you checking the "L" connector with the engine running? If so, you shouldn't be pulling that connector off the alternator with the engine running.

 

Is "L" the exciter wire connector? If so the original connector broke off a few years ago and I soldered a new one on. I ripped the shrink tubing of the repaired section of wire and have been using the voltmeter on it.

Looking closer "L" is the exciter wire and I've done the tests and it ways to check alternator and battery. I am going to take in the battery to test.

Looking closer, "L" is the exciter wire and I've done this test and it says to look at the alternator and battery. I am going to take the battery in for a test.

 

What year is your car? Edit:'95...from above....

Yes to your L question...as I understand it so far...but the schematic makes me raise an eyebrow as to if I might missing something with how it's wired internally. I am fairly certain that it is involved in supplying a field for the rotor. As to how it's regulated, I'm not sure, but there appears to be some sensing circuitry that governs rotor field strength.

Are you absolutely sure the "L" connector is pinned for the right terminal? There are four possible connections in that connector.

With the battery and alternator electrically installed....the engine off, key to the on position, what voltage reading do you have at the end of the "L" connector with it removed from the alternator?

I get 11.6V volts on that check(at the "L" terminal). My battery voltage is 12.02V....as is the reading on the alternator charging post.

A bad battery can cause the car not to run even if the charging system is good. Had it happen on my brother's '99 V6 Camaro. Car would run for about a mile then shut off, I'd jump it, run for a mile shut off. We did that all the way to Autozone. They verified that the battery was bad.

Shortly before that he had an alternator go out.....I think one of the rectifiers in the thing went bad as all his lights were going bright, dim, bright, dim as the car would run.

If you are going to try the 470 ohm bypass deal, make sure the wattage of the resistor can handle the current running through it.

I feel like that troubleshooting chart should point you in the right direction.

The alternator you used from your friend....was it from a 4th gen LT1 F-body that runs just fine installed? Edit:looks like it was....

Are you sure that the alternator you bought, uses the same pinout(for the "L" wire) as the 140A OEM units?

 

Its unfortunate that factory service manuals just lead you in circles, mostly because, even they, can't fathom system interactions in the real world.

If the battery charges, holds charge and checks good with voltage and load test, and two good alternators(one proven good) along with a contrasting bad alternator, I would have to say you don't have a voltage problem...you have a component affected by voltage.

After reading your back story, its feasible for free rein ignition spark to damage the ignition control module(ICM), optispark or even the PCM.

 

Remote troubleshooting can be extremely challenging.

On almost any problem, when someone is trying to explain what is going on to me I have to tell them let me have a look at it before I can get a really good idea of what is going on.

I think the factory charts are pretty good, but they certainly can't account for all the stuff that goes on in the real world.

At this point, we need to make sure that the alternator is getting the right inputs from the right sources. If those are good, then he may need to take it to the next level with a good tech(on site with the right tools) to isolate what is giving him so much grief.

If there is resistance in his repair of the "L" wire that might be causing issues...but the bad alternator before hand is not good either....as we are not sure how high the voltage could have spiked.

Since it runs like a champ on battery alone, I think the problem revolves around the electrical connections to the alternator. I don't think a 2 volt bump would cause components to go bonkers(provided that the battery was maintaining 12V during it's solo run), but I certainly wouldn't rule it out....it would just be really far down on my hit list of things to check at this point.

 

Today I got the battery tested. I didn't think it was the problem and it isn't. It tested 13V and 66% capacity. Just to eliminate it from the equation I borrowed (same guy as alternator) my buddies fresh as of last fall battery and it ran like **** with the new alternator. So I am eliminating the alternator and battery as the problem.

My mechanic friend (who is an LT1 owner) who tested the battery said alternator, battery, fusible links, PCM. I'm not sure it is the PCM as it works fine with the bum alternator.

As SS RRR mentioned above it should see a stable voltage and that is what I am going to try and get before ripping into everything else. 2-3 volts more should not power pumps, injectors, tune, etc. to the point where it runs so badly. You would think the computer could compensate at least to idle.

So battery and alternator are off the list. Next up I am going to look at the exciter wire and SNM above suggested.

 

Yeah, pretty sure it is wired on right. It is only one wire and of the 4 pins in the connector only one is "alive" and sees the same voltage at the connector pin as in the break in the wire.

Looks exactly the same as my OEM one. I can check closer.

 

To test that theory, start it with the alternator disconnected so its running well then turn on the battery charger to increase voltage. A trickle charger/battery tender may not do the trick. You could also try jumper cables to another running car.

I went back and read your original post. One thing you mentioned was a warning light blinking on your ignition box. For what reasons will that light turn on? If not sure, what brand and model number is it?