Low Pressure Fuel Pump
Feeds fuel from the tank to the HPFP. If it can't supply enough volume, the HPFP starves and pressure drops.
Why it matters
The LPFP is the first link in the fuel supply chain. If it drops below ~60 PSI, the HPFP cannot build sufficient rail pressure.
What to look for
LPFP pressure should hold above 65 PSI under sustained WOT. Below 55 PSI is critical. Upgrading LPFP is often needed before Stage 2+.
Related terms
Pressurizes fuel to ~2,900+ PSI for direct injection. When it can't keep up with demand, fuel pressure drops and the engine runs lean.
What percentage of available time the fuel injectors are open. Above ~85% means the injectors are near maximum capacity.
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