Description And Operation

When the Powertrain Control Module (PCM) receives a START or RUN signal, it energizes the Fuel Pump Relay which sends a continuous 12 volt supply to the Fuel Pump Control Module (FPCM). The PCM also sends a Pulse Width Modulated (PWM) control signal directly to the FPCM which regulates the PWM voltage that will be sent to the Fuel Pump Module. The PWM will vary from 10-100% depending on the input of the Fuel Rail Pressure Sensor and other engine demands. The PCM receives a PWM signal from the FPCM representing the state of all inputs and outputs of the FPCM. This system is a variable pressure fuel system. The pressure can change during different modes of engine load and operation. Ambient temperature and fuel temperature can also contribute to fuel pressure changes. The pressure is raised during high ambient temperatures to prevent boiling of the fuel. If a pressure sensor fails or other failures are present; The duty cycle goes to a default setting (80%) to maintain fuel pressure.