Why won BBK fuel pumps and fuel regulators work on a 1998 and up Mustang?
A. In the 1998 model year, Ford switched their fuel system to a return-less system. The model years previous to this used a physical regulator and a constant-velocity fuel pump to regulate the pressure throughout the system. The old-style system constantly supplies a fairly standard pressure (depending on load), the regulator only allows a certain amount of that pressure into the fuel system, and the excess fuel and pressure is bled back to the fuel tank. On the newer design, the fuel pump is a completely different design that works with varying pulses of voltage, and the computer monitors and controls the fuel pressure. Basically, the ECU (Engine Control Unit) controls the fuel pressure by telling the pump to speed up when the engine is under load, and tells it to slow down when you are just cruising, constantly varying the pump speed to control pressure in the system. While the newer style pumps can be adapted to be used in older applications, the older-style pumps and systems will n
