Apparently the newer Beetle fuel pumps put out too much pressure and this can overwhelm the carb and force fuel into the system causing flooding and hard starts when warm. Additionally, for dual carb setups, older pumps may not put out enough fuel to handle them. Here is some information on electric or proper mechanical pumps.
Best quiet electric fuel pump for a 72 SB?
CARTER 12V ELECTRIC FUEL PUMP KIT
Carter Fuel Systems Carter Universal Electric Fuel Pump Automotive Replacement 12V (P90091)
Electric Fuel Pump