leaking fuel pressure

[shadowpwr]

I have a '97 Cavalier 2.2 OHV with a slight problem. Lately the fuel pump gets really loud after driving the car for awhile. It seems that the hotter it is outside the louder the pump gets.

I've checked the fuel pressure both running and static and are within the specs. The only thing that is weird is that the pressure slowly leaks to zero after turning the key off. Takes about 5 minutes for it to reach zero. The manual says that the pressure should stay between 36 and 42 psi for at least 10 minutes. The only thing I can think the problem is a leaking injector or two. Also if I pinch the return line the pump quiets right down.

Any help with this would be greatly appreciated.