What is an FMU?
A fuel management unit is a fuel pressure regulator. The FMU works 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. The factory electronic controller can't compensate for this increased flow (it wasn't designed for supercharger use) so another way was found to supply the additional fuel needed: the FMU.
Installed just down from the stock fuel pressure regulator, the FMU doesn't control fuel pressure until 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 Vortech Supercharging Systems are smog legal is because the stock controller is retained/unmodified and, at part throttle, engine performance and emissions are not affected.
SUPER FUEL MANAGEMENT UNIT
Vortech's Super Fuel Management Unit (SFMU) is a tuner's dream. It permits complete tailoring of the fuel pressure curve relative to manifold pressure, including upper and lower limits. The Super FMU can be used in a series or as a stand-alone component. Its super high-flow capacity can handle large single and dual pumps while fluctuation and pressure creep is eliminated. The unit can also be used to adjust static pressure. Features include four pre-calibrated gain ratios of 7:1, 5:1, 3.25:1, and 2.5:1. Easily replaces standard non-adjustable FMU.