Work out fuel pump flow instantly with clear inputs, formula shown and shareable results.
Pump flow starts from the same BSFC calculation as injector sizing, converted from mass to volume by fuel density and increased by a safety margin. That margin matters because pump flow falls as fuel pressure rises and as voltage sags under load.
Fuel pump flow
mass flow = power x BSFC; volume flow = mass / density x (1 + margin)
A pump's flow-pressure curve is falling. A pump rated 300 L/h free-flow might deliver only 200 L/h at 4 bar, so ratings must be read at working pressure.
Considerably. Flow falls roughly with voltage, so a pump tested at 13.5 V delivers noticeably less at 12.0 V with poor wiring.