GFB FX D Low Pressure Fuel Regulator w 8AN Ports Easy Medieval Shield Designs. For engines that use an EFI type pump with a carburetor, the GFB FX D LP bypass regulator is the perfect solution for fuel delivery. Dual 8AN inlet ports offer installation flexibility, whilst the two 1 8" NPT gauge ports allow the use of both a mechanical gauge and electronic pressure sensor if required. The FX D LP features a Teflon valve seat for superior fuel pressure retention after shutdown, leading to easier starting. We also use a double layer reinforced diaphragm and stainless steel valve that offers a burst strength in excess of 500psi!