I bought an 81 Chevy truck 305 that I've had a few problems with. It originally had a fuel problem where it would run fine, then it would stall when warm. Once it started up again it would miss and billow black smoke from the exhaust. My first cure was to replace the gas caps, thought there was a venting problem. That didn't help so I replaced the quadrajet and manifold with a Holley 600CFM. I know thats pretty big for the engine size, but I eventually want to put a bigger motor in it. It still had the fuel problem. This truck was equipped with a charcoal cannister and whenever it stalled, gasoline would overflow from the cannister, very strange. I thought for sure it was the fuel pump when I saw that so I replace it with one with 2 fittings instead of 3 to eliminate the cannister, no luck there either. I replaced the coil for good measure, but now i'm stumped. I had a some great advice with my starting problem in this group, maybe I can get some good advice with this problem. It would be greatly appreciated.
Now it either puffs a little smoke and runs so-so or it pours out black smoke. it seems like the carb is just getting flooded with fuel.