Fuel pumps work electronically via an engine control unit, which regulates the quantity of fuel delivered based upon instantaneous information obtained from a number of sensors. Data that may include RPM, throttle position, and even oxygen levels will be constantly scanned by these sensors and forwarded to the ECU. For instance, during high revolutions or upon acceleration, the ECU instructs the fuel pump to increase its duty cycle to pump more fuel into the system for correct air-fuel mixture ratios. Conversely, the ECU will reduce pump output during no activity or low demand periods, conserving energy to support frugal fuel consumption.
Most fuel pumps today are of the variable-speed type, allowing the ECU to change the fuel pressure on the fly. Most normal engines have relatively low fuel pressure, ranging from 40 to 60 PSI, but in performance applications, as much as 80 PSI may be used. The ECU works in concert with the pump to ensure the delivered pressure meets the requirements of the engine for balanced combustion and to prevent fuel starvation. ECU-controlled variable-speed fuel pumps can realize economy gains of about 5%, since they use less power when supply demand is low. As with DISC, such systems can be installed without penalty to fuel economy.
The relays in electronic fuel pump control perform a very useful function. The ECU initiates the fuel pump relay, through which control of the 12-volt feed to the pump is achieved. Its failure would render the ECU incapable of carrying out the control in fuel delivery as desired; hence, starting troubles or intermittent flow may be experienced. Periodic testing of the relay helps to keep the connection proper between the ECU and fuel pump for assured power transmission.
All high-end and high-performance vehicles have an extremely sophisticated electronic control of fuel pumps. Performance-oriented ECUs can make use of fuel maps-preprogrammed settings for delivering variable amounts of fuel based on different conditions. For example, if there is a need for rapid acceleration, the ECU would draw upon a fuel map programmed to deliver full fuel flow, eliminating any lean mixtures to allow peak horsepower output. AEM and Haltech have models available that have programmable fuel maps and give the enthusiast the capability to fine-tune the Fuel Pump setting for any possible driving scenario, from commute mode to full-on racing. In brief, this electronic control via the ECU will enable precise adjustments in fuel flow to guarantee constant pressure, increased efficiency, and an optimum performance of the engine in any condition.