UHP fuel pump

An ultra-high-pressure (UHP) fuel pump is a fuel injection pump that delivers fuel at the very high rail or injection pressures, above about 1,500 bar, used to atomize heavy fuel finely and lower particulate and smoke on modern engines. It is the high-pressure source in a common-rail two-stroke or in a UHP four-stroke injection system, built as a plunger pump driven off the engine, often with several elements feeding one rail. Higher injection pressure shortens the spray penetration time and improves mixing, which helps the NOx-versus-fuel-consumption trade. The term distinguishes these pumps from the lower-pressure circulating and booster pumps in the fuel-supply line.