1990 EF with B20 swap. Car ran fine...took it to get gas...came back...noticed a stutter a couple times....pulled into the drive and the car dies. Car would crank and crank and nothing. Messed around with grounds and unplugged main relay and plugged back in. Car popped from exhaust and fired up. Took the car for a little drive, then took it to the grocery with no issues. Next day go out to drive to work, make it around the corner and the car dies. Started right back up...drive a little bit further thinking it was a fluke.....car dies again. No stutter or anything, just dies. Continues to die on my way back home to get my daily. I installed a new battery the day it first wouldn't start....little car audio battery. I noticed the main relay clicked loudly when attaching the power cable. I'm thinking the main relay?

 

I think tour battery is too small.If I'm reading this correctly,you swapped out your bigger battery for a lightweight one and that's when the problem started?

 

It wasn't an issue at first.....the little battery started the car fine. Kinetic HPM-800 I think....then the car slowly started draining the battery to the point that if I drove it to work, I'd have to use a jump pack on it at lunch time. I swapped the battery out for a replacement and it seems to hold the charge far better, but still after an overnight, it won't start without a jump pack. I'm going to get a "real" battery asap, but I feel like that's not really the issue since I drove the car for months with a battery that was worse.

 

I would swap the battery out for a 'normal' one.A lot of the lightweight ones require a battery charger/maintainer like the C-Tek ones to be on overnight,everynight.From what i know they just aren't worth the hassle for a daily.

 

Went and started the car last night....had to jump it of course as the battery is totally dead.....it ran for a solid 10 minutes or so, then died. Battery dead...barely any juice at all...just clicks....jumped it again and it just cranks over and over....mash the pedal to the floor while cranking and it pops loud from the exhaust and fires up. I didn't let it run long enough to die that time. I guess I need a new battery at the very least... This Kinetik battery is brand new too.

 

Your alternator.

 

I thought that too. Just bought a real battery. Ran for a few, died... Started back up.. Died.... Got it running for a while.... Took it around my neighborhood and it died. Tried to start and it made a loud terrible noise and now I can't get it started. Nothing looks amiss under the hood... Nothing under the car. Nothing obvious. Damnit

 

99% alternator.

doesn't matter that the battery is small alternator should keep engine etc running.
alternator should charge up battery and be good enought to run car without battery
you have battery only to start engine in track cars i have small motorbike battery in my car for 25bucks.

 

Great information but seams only feasible really in a track car,don't think I would have faith in the small motorbike battery for a daily.Saying that,new alternator,new motorbike battery and always take my jump starter battery pack and I would do it . Probably sheads 9kg or so... that WOULD be sweet.

 

Your alternator.
​​​​​​​And might as well change out grounds because old.

 

I don't think so.....I've had alt belts slip off or fail and the battery light will come on and I've been able to drive until the battery drains. The car won't even start now. I'd be willing to bet somehow the dizzy failed. A distributor failing cause these symptoms?

 

The plot thickens.

 

There is an ICM in the distributor that would cause an intermittent failure before it finally dies and never works again.

The story you have provided thus far is that you can drive the car on a fresh battery and then it dies after a bit or running.
After continued use, the car will eventually fail to start.
With THAT story, it all aims to the alternator or a bad alternator circuit (bad or missing grounds are common fail points).

 

The car will no longer start at all. The battery continues to crank strong. It died that last time and I cranked it again, it fired up but made a terrible noise from under the hood and then wouldn't start, From my experience, I can disconnect the alternator entirely and the car will run until the battery drains completely.

 

You are missing the point of an alternator and battery with the car running.
The battery does most of its work when you crank the engine on start up.
Then then alternator comes in to keep the battery charged up.

Of course you can remove the alternator and run on battery.. until the battery dies.
BUT - once you have the engine started, you can remove the BATTERY and the alternator will continue to run the car for a good long time as well.

From what you had wrote, this does not seem like it was happening.
It sounds like your battery was losing charge and your engine was shutting off.
Very common issue when the alternator is faulty.