The gauge is not liquid filled, however I don't have another gauge to compare it to for accuracy. I didn't install a fuel pressure regulator because when I called edelbrock about the problem with my first two pumps, I was told that I didn't need a regulator with that pump and that there was no way to adjust the pressure of the pump. I didn't install a regulator after that either because I figured it would only be masking the problem of the pumps being that they are only supposed to make 6 psi max and not 9. I will try to get a helper tomorrow to keep it running so that I can look down the carburetor and see whats going on.