I heard a buzzing while idling the engine earlier today.  It was an
intermittent buzz (on a couple of seconds, off a second, sometimes cycling
in fractions of a second).  Thanks to being on this list all these years,
I knew to suspect the fuel pump.  What I don't recall is if a buzz means
the pump is on its way out, how long it will keep going once this starts,
or what other issues ought to be considered.

I just changed the fuel
filter a couple of weeks ago, and though I have some funny high
idle (~1400, occasionally dropping to 1000 for a fraction of a
second....problem sometimes disappears when engine has enough time to warm
up) issues, it runs fine otherwise.

Thanks for the help.
David