You shouldn't be getting any junk past the filter on the fuel pump. Does it still have a screen in it? Also, check the flow on the pump. I stick the fuel line in a pop bottle and have someone crank the engine. Can't recall how much fuel should flow, but a good pump will fill up a 2 liter bottle in a couple of minutes. When I replace the pump on my 52, the pump warranty was no good if I didn't have a filter before the pump. If you do that and use a canister filter with rubber hose, seal the connections with Permatex Hylomar. Even with all of that, it sounds like your carb probably is full of junk and needs cleaning.
