1999 Sebring conv. fuel pump?????

I posted a few months ago about my moms sebring that would not start. I ended up replacing the fuel filter at the tank...and it started fine and has worked ever since...........UNTIL now. It wouldn't start the other day. I remember reading on here or somewhere, where a mechanic said he tapped the tank with a screwdriver...and it started(fuel pump related, i guess). So...just out of frustration i tapped(not hard) the fuel filler cap with a hammer(laugh here!)...and it STARTED! It wouldn't start yesterday at Hyvee...so i went over, tapped the fuel filler cap again...this time nothing. I then laid underneath and tapped the fuel tank about 8 times. BINGO!....it started right up. I am not totally car stupid. I have been telling her "i THINK it is something with the fuel pump OR sending unit". When it wouldn't start......i heard NO electric fuel pump wine from back there. Before it ACTUALLY did start...EACH TIME...i heard the pump upon turning key. Any ideas?........ I basically hate to tell her to buy a $200-300 pump and then it's something else. I am about 95% sure it needs a new pump. But i think you can buy the pump seperate from the whole thing. wOULD I HAVE TO REPLACE THE WHOLE THING?....THANKS EVERYBODY!!!!!!!!!!!!

there are some recalls on some fuel pumps take to the dealer or call go to google and type in 1999 Chrysler Sebring Recalls and read through there is also a number you call call.
hope this helps good luck