Check theSamba. If I recall the is a thread about this. Notwithstanding possible restriction by the tank screen you can still get a buzz. I have a new tank, new pump and I have a buzz. I have changed the filter, changed the pump again and still have a buzz.   Apparently even new fuel pumps can buzz if they don't get enough fuel and there are two outlet sizes on the tanks. The small one is worse. The "fix" is to use a resistor (and you want to review the thread to keep temps safe) to slow the pump, thus reduce the cavitation issue.

Ian