Strange Sounds

[Jason Puckett]

Lately my '93 has been making strange noises.  It
seems to be more when its hot out (Arizona summer).
After I turn the car off within a few seconds I get a
humming noise from the fuel pump.  It will hum for
about 10-15 seconds and stop for 10-15 then start
again.  Sometimes it only does it once or twice but
sometimes it will keep doing it for a few minutes.
Yesterday I sat there and listened to it, it kept
doing it over and over.  I finally got out and opened
the gas cap, it released the pressure in the tank and
then I didn't hear the hum anymore.  Anyone ever had
this problem?  Think I should worry about it or is it
something to ignore?  Is my car going to explode?!?
Thanks