humming sound - fuel pump?

new used car- 97 'scort with 33k

doing a lot of work on the car this evening i noticed that there was an obvious humming sound coming from the car that i hadnt noticed before. it sounded like it was coming from the area of the fuel pump. it sounds like a humming/whining, not too loud (woudlnt be able to hear it while driving, for isntance). i never hear this sound on my last escort, though.

could it be a stressed fuel pump?

history: i just change the fuel filter this afternoon. i also wired in a kill switch inline with the inertia switch (as an anti-theft device), but used what i think was a pretty hefty switch with heavy guage wire. car idles fine, but havent driven it yet with the new filter.

any ideas? anyone heard this before? id much rather change out the fuel pump now than on the road the day after tomorrow, but id sure rather not change it at all if i didnt have to.

thanks, as always-
anthony

My Escort's fuel pump humms and whines. When I start it up when it's hot I even hear what sounds like air bubbles going through it. Has done it the whole 5 years I've owned the car.