I have mentioned this before on here as this question been asked
a few times before.
When I bought my cab my fuel pump buzzed real loud and also you
could hear with engine running from 6 ft away but it kept on working
for about a year with the odd misfire and the odd non starting when hot.
When I came to replace it the ford dealer wanted 120 Malta pounds,
and through my mate who is a mechanic got the same spec pump
from Germany for 45 Malta pounds including postage.
When we replaced it he reckoned it was also the original pump
and now you can just hear a very low buzz when its in the garage
you cannot even hear it when its outside, at the same time I also
replaced the fuel filter, this should be replaced at least every other year.