The truck has a glass bowl fuel filter just ahead of the carb so wouldn't any junk in the system show up in there (which it isn't)?
Also, the truck has a new tank and new fuel lines. I'm wondering if rust inside one of the passages in the carb could have broken loose and clogged something up since the Carter W-1 carbs are mostly made of cast iron, or maybe some other debris not cleaned out in the rebuilding process.
