Fuel Metering System

BASIC SYSTEM OPERATION
The fuel metering system starts with the fuel in the fuel tank. An electric fuel pump, located in the fuel tank with the gauge sending unit, pumps fuel to the fuel rail through an in-pipe fuel filter. The fuel pump is designed to provide fuel at a pressure above the pressure needed by the fuel injectors. A fuel pressure regulator in the fuel rail keeps fuel available to the fuel injectors at a constant pressure. Unused fuel is returned to the fuel tank by a separate pipe.

(3X) REFERENCE PCM INPUT (CKT 430)
From the electronic ignition module, the PCM uses this signal to calculate engine speed and crankshaft position. The PCM compares pulses on this circuit to reference low CKT 453. The PCM also uses the pulses on this circuit to initiate fuel injector pulses. If the PCM receives no pulses on this circuit, no fuel injection pulses will occur and the engine will not run.

CAM SIGNAL (CKT 630)
The PCM uses this signal to determine the position of the #1 piston during its power stroke, allowing the PCM to calculate true Sequential Multiport Fuel Injection (SFI). A loss of this signal will set a DTC P0341. If the CAM signal is lost while the engine is running, the fuel injection system will shift to a calculated sequential fuel injection based on the last fuel injection pulse and the engine will continue to run. The engine can be restarted and will run in the calculated sequential mode as long as the fault is present with a 1 in 6 chance of being correct. Refer to DTC P0341 CMP Sensor Circuit Performance. Testing and Inspection