Fuel pump?

My daughter has a 05 Chevy Classic. A couple
months ago it died on her after sputtering for a
second, then after a couple tries it started up and
stayed running. We took it to the parts store and
had it put on the computer, it read either a purge
valve or purge sensor, both of which I believe to be
part of the fuel system. It has ran fine since then
until a couple days ago, it did the same thing
except it won't start at all now. The people I've
asked about it insist it's the fuel pump, I'm hoping
it's the much less expensive sensor or valve.
Opinions are welcomed and needed! Also my sister
has a 99 cutlass that she's about to scrap, would
that fuel pump be compatible? The cars are very
similar .