In an internal combustion engine, a method of controlling the pressure of a fuel accumulator volume which supplies fuel under pressure to one or more fuel injectors, comprising:
i) determining or measuring the actual pressure at the inlet manifold; and,
ii) determining an accumulator volume pressure based on the results of step i). The accumulator volume may be a common rail. The method may include determining the difference between the actual inlet/manifold pressure and a scheduled inlet /manifold pressure, and determining the accumulator volume based on this difference.