High-Pressure Fuel Pump (HPFP)
A mechanical pump driven by the camshaft that pressurizes fuel to extreme levels for direct-injection engines.
The High-Pressure Fuel Pump (HPFP) is a core component of modern gasoline direct injection (GDI) and common-rail diesel engines. Unlike traditional fuel pumps located in the fuel tank that operate at 40 to 60 psi, the HPFP is mounted directly on the engine block and is driven by a lobe on the camshaft, pressurizing the fuel to levels exceeding 2,000 to 30,000 psi.
This extreme pressure allows the fuel injectors to spray fuel directly into the high-pressure environment of the combustion chambers as a super-fine mist, improving fuel atomization, power, and emissions. The pump relies on the fuel itself for lubrication and cooling.
HPFPs are subject to severe mechanical wear. A common failure mode is the wear of the mechanical follower that rides on the camshaft lobe, which can damage both the pump and the camshaft. Symptoms of a failing HPFP include engine hesitation under load, hard starting, a check engine light with fuel pressure codes, and fuel leaking into the engine oil. Regular oil changes help protect the camshaft and follower from wear.