Fuel pump pressure is important because it will have a direct effect on your engine’s ability to create the ideal air fuel mixture that is integral to combustion efficiency. Fuel-injected systems generally require fuel pressures between 30 and 60 psi in order to deliver balanced combustion within the engine. Inadequate pressure would mean that fuel delivery becomes unpredictable, and you end up with a “lean” mixture (too much air, not enough fuel). Lean mixtures also keep about 15% of the horsepower from ever materializing, cut acceleration performance and cause rough idling and stalling.
Correct fuel pressure will properly open the injectors at the correct intervals with delivery of fuel at the appropriate rate. The injectors may cease to work other than directly from the pressure 10% below the recommended point and not provide uniform fuel flow. Fuel efficiency falls by up to 10-15%, meaning instead of burning 1 liter per hour, the engine now consumes as much as 1.5 litres because it burns more fuel to maintain enough power due to the lower injectors opening times. Also poor pressure control causes excess fuel usage and higher emissions (not good if your vehicle must meet OBDII emissions)
Even higher fuel pump pressure requirements are needed for high-performance engines, especially if they're turbocharged or supercharged. These motors operate with pressures over 100psi, as the added fuel output necessitates supplying that to sustain the drive demands or else fuel starve. Performance fuel pumps are built to keep up with these increased pressures, and can flow 255 liters per hour (LPH), or higher, to accommodate the power requirements of high-output engines.
Improperly burnt fuel due to a partial burn in the engine can also impact other parts of the engine including the spark plugs and cylinder walls [2] because these harmful residues are typically present at low fuel pump pressure too. Eventually this wear will decrease the life of the engine, as it is putting additional strain on the combustion process by doing more work to produce power. Mechanics repeatedly reinforce that “fuel pressure needs to be consistent or else the engine will have to work harder” because running short on fuel only leads to bigger, more expensive damage in the long run.
Throttle response is another area in which driver often notice benefit from proper fuel pump pressure; proper fuel flowrate allows the ECU to achieve that smooth, responsive acceleration. The worst part of having a fuel pump that does not provide the pressure it should is when you step on the throttle; it gives delays or just hesitation which definitely affects the drivability of your car. Reconditioning, like the replacement of a fuel filter every 20 to 30 thousand miles also means that pressure from the fuel pump remains steady, which can enhance both performance and economy.
Engine operation will generally be less efficient and more rough with a lower fuel pump pressure. If pressure drops, the fuel pump will work too hard which will shorten its life and eventually cause it to fail. Bypassing any pressure problems will help protect the engine and its performance, as well as avoid those expensive rebuilding costs down the road when nobody has been minding those fuel systems. To learn more about fuel pump care and standard pressures, visit Fuel Pump.