1984 GL-10 Hardtop Coupe FWD.  EA81, Carter/Weber carburetor. Fuel pump isn't operating.  If I provide fuel down the carburetor the engine will run properly until I stop fueling.  Replaced fuel pump, and distributor (to provide proper ignition signal, the shaft had some play).  I'm focusing on the Fuel Pump Control Unit (FPCU), but I'm not in a position where I can afford to experiments with a $150 new one without being fully convinced that it will remedy my situation.  I need actual diagnostic