Fuel Tank and Lines

The fuel pump driver module (FPDM) controls the fuel Delivery Module (FDM) in a returnless system. The Powertrain Control Module (PCM) gets input from the fuel pressure sensor in the fuel rail and temperature readings from the Engine Coolant Temperature (ECT) sensor and the Intake Air Temperature (IAT) sensor. The PCM then sends a duty cycle signal to the FPDM which results in variable speed fuel pump operation.