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Home >> Cadillac >> 2004 >> CTS Base, 3.6 7 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls - 2.6L & 3.2L - Troubleshooting & Diagnosis) >> Troubleshooting >> Fuel System Diagnosis >> System Description

System Description

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When you turn the ignition switch to the ON position, the engine control module (ECM) enables the fuel pump relay, which in turn powers the fuel pump. The fuel pump remains ON as long as the engine is cranking or running and the ECM receives ignition reference pulses. If there are no ignition reference pulses, the ECM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position, or if the engine stops.

The fuel tank stores the fuel supply. The fuel pump is an electric pump that is attached to the right fuel tank module assembly. The fuel pump also supplies fuel to the siphon jet pump, also attached to the right fuel tank module. The siphon jet pump draws fuel from the left side of the fuel tank to the right side of the fuel tank. The fuel pump is designed to provide fuel at a pressure above the pressure that is needed by the fuel injectors. A fuel pressure regulator, which is also located in the fuel tank, is attached to the right fuel tank module. The fuel pressure regulator keeps the fuel available to the fuel injectors at a regulated pressure. The port on the fuel pressure regulator is an atmospheric vent. The fuel pressure regulator does not compensate for changes in intake manifold vacuum. Unused fuel is returned from the fuel filter to the fuel tank by a separate fuel return pipe.