Abstract: A single spot fuel injector is energized only twice per revolution of the crankshaft of the engine so that under given operating conditions the injections coincide with the TDC and BDC positions of a piston of a selected cylinder of the engine. Under higher engine speed operation, the injection timing is advanced to improve the fuel distribution to the cylinders. When the engine operates at an engine speed below a predetermined level it is possible for the injector to be energized three times per revolution of the crankshaft.

Abstract: A disc having first and second sets of markers thereon is rotated in sychronism with the crankshaft of an engine so that pickups associated with the disc produce pulse trains of two and three pulses per revolution of the crankshaft respectively. A circuit responsive to either the speed or load of the engine selectively connects one of the pulse trains to a fuel injection control circuit to induce the fuel injector to inject in synchronism with the pulses of the selected pulse train. Alternatively the pulses outputted by the ignition system are frequency divided and fed to the fuel injection control circuit.

Abstract: Disclosed is a fuel/air mixture supply system for an internal combustion engine of the single-point fuel injection type wherein, the intake manifold system is formed with a first fuel/air supply passage which inspires atmospheric air and which has fitted generally at a midpoint thereof a fuel injection valve which injects fuel into the inspired air. The fuel/air mixture then proceeds to a first set of branched passages, each one of which conducts the fuel/air mixture to a cylinder of the engine. Further, there is provided a second air supply passage which inspires atmospheric air and which branches into a second set of branched passages, each one of which conducts air to a cylinder of the engine. The first fuel/air supply passage is smaller than the second air supply passage, and the first set of branched passages are smaller than the second set of branched passages.