Have you tried turning on the fuel pump and see if the fluctuations stop?

Quote Originally Posted by GDFlyer View Post
I have a similar issue with my FX-3. Please let us know what you find.

I don't know anything about the orifice you mentioned, but ill see variations in fuel psi of 1-2 psi at lower power settings, 23/2300. At a higher power setting, 25/2500, is when I see larger swings in psi that are rapid and constant. Any where from 3-6 psi while the fuel flow stays consistent down to the tenth.

For example at a power setting of 25/2500 without the electric fuel pump on, fuel psi varies between 19-23 psi but will periodically have more drastic drops or spikes. Same with the electric fuel pump on, except the pressures are bouncing more between 25-30 psi. Again, in both of these scenarios fuel flow stays constant.