20 SENR9977 Systems Operation Section g01133212 Illustration 22 The timing wheel and the secondary speed/timing sensor (32) Secondary speed/timing sensor (33) Timing wheel The ECU for the fuel injection pump is mounted on the top of the pump. The ECU has a connection to the engine ECM and a connection to the speed/timing sensor. The ECU has a connection for the two solenoid valves. The ECM functions as a control computer. The ECU calculates the optimal parameters from the ECM data. The fuel solenoid actuates the valve accordingly.
g01133213 Illustration 23 Operating principle (34) Angle of fuel delivery (35) Lift of the cam (36) Stroke (37) Pulse for actuating the fuel solenoid (38) Valve lift (39) Angle of the speed/timing sensor The secondary speed/timing sensor in the fuel injection pump determines the precise angular position and the speed of the fuel injection pump shaft. The timing wheel (23) is permanently connected to the fuel injection pump shaft. The secondary speed/timing sensor gets information from the timing wheel. The sensor then sends electrical impulses to the ECU. The ECU also uses the information to determine the average speed of the pump and momentary speed of the pump.
The amount of fuel is proportional to the stroke of the piston. The effective stroke is proportional to the angle of fuel delivery. A temperature compensation takes place in the ECU. The compensation takes place in order to inject the precise amount of fuel. Shutoff The engine shuts off by interrupting the fuel supply. The engine Electronic Control Module (ECM) specifies the amount of fuel. The fuel solenoid valve is switched by the ECU on the fuel injection pump to the zero fuel position. Note: The engine will not run if the secondary speed/timing sensor fails. The signal of the speed/timing sensor is constant.
Power command signals are routed over the CAN data link from the engine ECM to the ECU on the fuel injection pump.