Fuel Pump Relay: Description and Operation

When the ignition switch is turned to the ON position (before engaging the starter), the PCM energizes the fuel pump relay for two seconds, causing the fuel pump to pressurize the system. If the PCM does not receive ignition reference pulses (engine cranking or running) within two seconds the fuel pump relay will be shut off, causing the fuel pump to stop. Refer to Fuel Pump Electrical Circuit Diagnosis.