[W126 Coupe] fuel pump buzzing

[Shayegan, Richard]

Starting a few days ago my fuel pump does some rattling when I start it
cold, but after a minute smoothes out. Today, when I parked, I noticed
that the pump was making quite a bit of buzzing noise and when I went
out and checked this not only was it buzzing but it was also vibrating,
and the exhaust was coming out in puffs (sounding like a quieter version
of a top fuel dragster). Is there anything I could have snagged when I
was running new speaker wire in the runways that could have caused this?
If not, is there anything I should be mindful of when replacing the fuel
pump?
Thanks,
Richard