Ensure that fuel filter is not blocked & replace if suspect. If good then, ......

Disconnect the fuel line at the inlet side of the fuel pump. or the fuel filter.
Remove fuel cap.

Blow into the fuel line, you should be able to blow right into the fuel tank.
Eyes bulging & face turning purple? The fuel line would therefore be blocked. If possible, use low pressure compressed air to blow back, but if not, disconnect fuel line at fuel tank & try again. This will tell you if a blockage is in the line or tank. Once identified, rectify as required, then fit new fuel filter & cary a spare in the glove box, you may well need it as any rubbish disloged will eventually find its way back into the line.

If all of this is good, then disconnect fuel line at carb & blow through from the inlet side of the pump. If all tests well, then connect a hose to the carb & blow. Ensure that fuel bowl is empty or well down when doing this one.

By breaking the fuel supply line down into sections you can determine the status of the whole thing & identify the part that's causing the problem.