My 1950 3100 did same thing...very small crap passing into carburetor from tank. I put an in line filter on it . I cut the rubber hose at bottom of tank to hard line. (Note I already had the AC glass filter at fuel pump) Does not filter FINE particles. Problem SOLVED instantly. Also amazing the tiny debris in the in line filter you can see from your tank. See pictures. The picture with Debris is only driving it a few days!
