Abstract: A fuel system for an engine has a first summing amplifier to which are fed signals representing demanded and actual values of the output of a pump supplying fuel to the engine, together with a signal representing engine speed. The summing amplifier compares the signals it receives and produces an output controlling the output of the pump, and there is also a second summing amplifier to which are fed electrical signals representing engine speed and a reference, a discriminator coupling the two summing amplifiers to a means for controlling the pump, so that the output from the discriminator at any instant is the output from the amplifier demanding the least fuel.

Abstract: A fuel system for an engine has a pump which supplies fuel to the engine and an actuator for controlling the pump output. The actuator is controlled by a control circuit to which are fed electrical signals representing demanded engine speed, actual engine speed and pump output. The control circuit sets the slope of the pump output versus speed curves of the engine, and speed-sensitive means operates below a predetermined engine speed for modifying this slope to make it shallower and so produce a smaller change in pump output for a given change in speed.

Abstract: An engine fuel system, particularly for a compression ignition engine, has a control arrangement for determining the quantity of fuel injected in accordance with the position of a control member such as an accelerator pedal. For part of its movement, the pedal produces an output which is a certain function of the pedal position, and for another part of the movement, an output is produced which is a different function of the pedal position.