S-10 zr2 fuel pump

I have a s-10 zr2 the veh pump is working and the motor will start, in the past the veh started very quickly, in the past week the motor will turn over several times before it will start, I can hear the fuel pump working, if I let the fuel pump run a few sec. Before I turn over the motor to start it will start faster, but not as good as before, is their some kind of check valve bad in the fuel pump and can a person just replace the pump not the hole sending unit.