258 fuel pump issues

    I replaced a fuel pump a while back and it worked great for a short time before it quit. It was an Airtex brand for a 258.

Sorry about that - I guess I missed the gas can part. My bad. I'd still make sure it's getting enough return air though.

At the risk of going too far astray, I do want to address one other issue which is a suitable replacement for the stock fuel pump. The fuel inlet tube came loose on mine one night just as I pulled into a cruise night an hour from home. I epoxy puttied it to no effect and it bucked and backfired all the way home, but I made it somehow.

I checked at several parts houses and of course the pump was barely available through special order. I never liked the puny looks of it anyhow and started thinking. While walking around the parking lot at the cruise, I happened to study the fuel pump on an early Mustang (sorry - I can't remember for sure if it was a 6 or 8 cyl, but I'm pretty sure it was a 6). As close as I could tell by comparison, the bolt flanges looked to be the same pattern, though I couldn't tell if there were any other differences. I took the old pump with me to an Autozone and asked to see the Ford 6 cyl.(?) pump. The bolt patterns WERE the same and the pump arm had relatively the same profile. The only difference I could see was that the Ford pump arm was about a half inch longer than the AMC. Since it wasn't an expensive pump, I bought it and took it home. I first tried a trial fit of loosely bolting it on the 232 and it fit! Next I carefully ground down the tip of the arm till it matched the length of the AMC on a bench grinder. I then chamfered all the edges nice and smooth and bolted it on. It fired right up and has been working flawlessly for about four years now.

I know this doesn't solve the poster's original problem, and I apologise for hijacking the discussion. But as these cars age, it is increasingly harder to find replacement parts for them. I do think it is helpful to share when someone finds a suitable interchange.

This is to some extent and answer that is driven by the intake manifold you are using. And then to the carburetor.
So exactly what intake manifold is in use and can I assume that the 600 CFM carburetor is a Carter AFB or ?
And you realize of course that a 600 CFM carburetor is big by a whole bunch
Using the formula that applies to applying a carburetor works out to a bit under 400 CFM at 5000 rpm. When I build an engine equivalent to the 258 AMC I use a 400 CFM Carter AFB. A 600 could very well give drivability problems.

manifold is Clifford, carb is holley 600 vacuum secondary, with the Mojo upgrades.   4.0 head swap, Isky cam, dual exhaust.