FUEL DELIVERY SYSTEM – Td6, DESCRIPTION AND OPERATION, Description. The wires to the fuel sensor are monitored by the ECM for short and open circuit. The ECM also monitors the V supply. If a failure occurs a fault is recorded in the ECM memory and the ECM uses a default fuel pressure value. If the ECM registers an 'out of range' deviation between the pressure signal from the sensor and the pre-programmed 'setpoint' a fault is stored in the ECM memory. Depending on the extent of the deviation, the ECM will reduce the injection quantity, stop the engine immediately or prevent further engine starting. NOTE: In addition to the low pressure supply to the high pressure fuel pump, the pressure in the fuel line is of equal importance with regard to correct fuel injection. The pressure in the fuel return line must not exceed 1.5 bar (22 lbf/ in 2 ). If the pressure in the return line exceeds this figure, the pressure differential across the high pressure fuel pump will be unbalanced and incorrect priming of the fuel rail will occur. The ECM does not monitor the return line pressure.
ENGINE MANAGEMENT SYSTEM – TD 18-1-26 DESCRIPTION AND OPERATION