not sure if my fuel pressure is correct
 

I recently checked my fuel pressure at the rail and found it was sitting pretty stready at 29-30psi (when idling) and then jumped to 40psi when I disconnected the vacuum. I'm pretty sure the pressure is suppost to be sitting at around 36-40. can anyone tell me what could be causing this and if there is an effective way to test the fuel pressure regulator seperately from the fuel pump. ohh and I just replaced the fuel filter and the result was still the same.