I had the accelerator pump tube experience too.  After I rebuilt the engine
for my 1972 Super Beetle, it ran very poorly.  I did this.  I did that.  I
even sat by the sputtering engine and wailed.  But I eventually decided
that it was the carb.  Looking at a picture of a PICT, I noticed that I
didn't have one of those curvy gas squirter tubes.  I fished around in my
solvent bucket and found it.

Vroomm, vrooom, VROOOOOOOMMMMMM....

I pressed it into place REAL HARD.  Maybe one can pein it in place with a
few taps.  This is also a cure for a loose brass tube where you attach the
fuel hose to the carb.

Wolf