Abstract: A fuel injection system includes a fuel body having a compact fuel chamber connected through individual flexible fuel tubes with separate fuel injectors mounted on the separate cylinder inlet passages of an engine. The system may have an integral fuel pressure regulator or the regulator may be located separately, for example with the fuel pump in a vehicle fuel tank. The pressure regulator may include a unitized diaphragm and valve assembly which may be dropped into a housing with a valve seat in the fuel body and enclosed by cover and spring means to form an integrated system. The unitized assembly can also be used in other applications. Pulsation damping may be provided by a flexible wall of the fuel chamber. The flexible wall may be the pressure regulator diaphragm or a resilient wall designed for the purpose.