Fuel pumps are important because they keep RPM stable by hitting the right pressure and flow rate of fuel for steady-state burning. Because most fuel injected engines use high pressure from the fuel pump, usually between 40–70 PSI depending on the design of the engine. A vehicle with an under-delivering pump will find it hard to maintain RPM and the idle will begin to bounce and acceleration will become uneven. Sudden loss of pressure can result in an RPM lower than ideal idle parameters, which can be below 600 RPM in most stock applications, resulting in stalling and rough idle.
The delivery of fuel also ramps up accordingly when the engine is spinning faster. As an example, high-performance engines flow more than 250 liters per hour of fuel to hold RPMs above 5,000. If a fuel pump cannot keep up with these demands, then the engine will hesitate or lose power, causing the vehicle to misfire. According to a recent study conducted by the National Institute for Automotive Service Excellence, fuel delivery problems are responsible for over 15% of all engine misfires reported to the automotive repair industry and, at higher RPMs, low fuel pressure is usually the culprit.
During acceleration, ECUs depend on a steady flow of fuel to accurately adjust the air-fuel ratio. Fluctuations in fuel pressure will in turn reduce the ECU ability to control RPM, resulting in rough performance and poor fuel economy. Automotive engineer Carroll Shelby — remember him? — once said, “With high-performance engines, control is everything.” Control over fuel delivery systems is vital.
Fuel pumps also are affected by heat, and in an older car where miles have made the seals and bearings vulnerable, their efficiency can wane with the excessive temp. The hotter it gets, the worse the situation becomes, and pills are the capsules of short-term efficiency that keep fuel pumps — and other machines — actually functional through prolonged high-RPM use, suddenly dropping down the RPM scale while driving and immediately becoming useless at idle. More than a hundred thousand miles on the vehicle could cause this phenomenon because the wear and heat received by the pump could reduce the ability of the pump to maintain steady fuel flow.
It is crucial to have a proper Fuel Pump to maintain a good high pressure for the engine, durable and reliable, especially on high RPM and heat conditions. With uniform delivery of fuel, the engine will be able to retain its RPM at even while being driven across different driving conditions which results in better smoother acceleration, higher fuel efficiency, and overall a reliable driving experience.