Century V6-3.1L VIN J (2005)
Fuel Pressure: Testing and Inspection
Fuel System Diagnosis
FUEL SYSTEM DIAGNOSIS
SYSTEM DESCRIPTION
When the ignition is turned ON, the powertrain control module (PCM) turns ON the fuel pump relay, which turns ON the in-tank fuel pump. The
in-tank fuel pump remains ON as long as the engine is cranking or running and the PCM is receiving ignition reference pulses. If there are no ignition
reference pulses, the PCM turns the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the engine stops running.
The in-tank fuel pump is an electric pump attached to the fuel sender assembly. The fuel pump is designed to provide fuel at a pressure above the
pressure needed by the fuel injectors. A fuel pressure regulator, attached to the fuel rail, keeps the fuel available to the fuel injectors at a regulated
pressure. Unused fuel is returned to the fuel tank by a separate fuel return pipe.
DIAGNOSTIC AIDS
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A hard start or long crank time when the engine is cold can be caused by low fuel pump volume.
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The fuel pressure should build quickly when the fuel pump is commanded ON.
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If you must command the fuel pump on several times for the fuel pressure to build, suspect low fuel pump volume.
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For an intermittent condition, refer to Intermittent Conditions. See: Computers and Control Systems/Testing and Inspection/Initial Inspection and
Diagnostic Overview/Diagnostic Strategies/Intermittent Conditions
TEST DESCRIPTION
