If your fuel pipes and filters have been in service for quite some time it is worth undoing the last joint in the line before the carburettor, turning on the petrol tap and letting the fuel flow for a while into a suitable container to check that you are getting a good flow. This can show up restrictions on in-tank filters, external filters and fuel pipes. Have a good head of fuel in the tank before checking. Old partially blocked external filters can show a reasonable flow initially due to the partially blocked strainer allowing the body of the filters to fill over time.