The Delphi F2p Ultra High Pressure Heavy Duty Diesel Common Rail System (F2p System) provides a cost effective upgrade path to an ultra high pressure common rail solution for heavy duty engines based on current electronic unit pump (EUP) technology. Driven by the engine's camshaft or mounted in a separate cam box, the enhanced electronic unit pumps constantly charge up the common rail to ultra high pressures. The pressurized rail provides the injectors with a constant source of ultra high pressure fuel at any engine speed, allowing the injectors to provide fully flexible injection capability, particularly related to close coupled small quantities.