Abstract: A fuel injection system operates under a substantially constant pump speed and creates multi-pressure levels by diverting the fuel flow. Fuel pressure can be switched from one steady pressure level to another level on-demand instantly. This superimposes and overlaps typical fuel injection events in the linear operating ranges under different pressure levels, significantly increasing the fuel injection dynamic range. Lower fuel injection when idle or during city driving reduces fuel consumption per mile traveled and reduces exhaust emission that causes smog in metropolitan areas. The system delivers additional power to the engine instantly at peak load on-demand, reduces idle speed with the engine running smoothly, does not change fuel tank temperature, and may enhance the life of the fuel pump.