What is an FMU?
The letters FMU stand for ''Fuel Management Unit''. Basically, an FMU is a fuel pressure regulator. The FMU is used on fuel injected, supercharged engines using the factory electronic engine management system. When an engine is supercharged the air delivered to it is greatly increased. For the engine to run properly and make max power a 11.5:1 air/fuel ratio must be maintained. Since the factory electronic controller can not compensate for this increased air flow (it was not designed for supercharger use) another way has to be found to supply the necessary additional fuel. The FMU is the device that does this. The FMU is installed just down stream of the stock fuel pressure regulator. It does not control fuel pressure until the engine manifold pressure comes under boost from the supercharger. As the manifold pressure increases, a pressure line from the manifold to the FMU causes the FMU to increase the fuel injector rail pressure. The increased fuel pressure causes the injectors to deliver more fuel to the engine. With this system the stock factory electronic controller can be used without modification on a supercharged engine with good results. The reason the Vortech supercharging systems are smog legal is because the stock controller is retained unmodified and at part throttle the engine's performance and emissions are not effected.

SUPER FUEL MANAGEMENT UNIT (SFMU)
The Super Fuel Management Unit has all of the features of the Fuel Management Unit and also features 5 separate adjustments that can be used to ''shape'' the fuel pressure curve. These 5 adjustments are:

The main spring adjusting screw

The calibration ring & disc

The vacuum screw

The optional bleed screw

The boost screw