i have 91 rs tbi, 5spd. after starting the engine, in about 2 minutes some strange continous humming sound starts to come from the driver back side near the rear tire, when idle and driving. when i turn off the engine the sound goes after 5 seconds.
is it the fuel pump? my friend says it is comming from differential
cant understand what it is,

 

It's the in-tank electric fuel pump.

 

ahaan, so its ok, i mean its normal cuz i didnt notice that sound before a month or two

 

sounds normal.