G5 L4-2.2L (2007)
Fuel Pressure: Testing and Inspection
Fuel System Diagnosis
Fuel System Diagnosis (RPO NT7)
Fuel System Diagnosis (RPO NT7)
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection/Initial Inspection and Diagnostic
Overview/Diagnostic Starting Point - Vehicle
Circuit/System Description
The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2
seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition
reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the
ignition remains ON.
The fuel tank stores the fuel supply. The electric fuel pump supplies fuel through an in-line fuel filter to the fuel injection system. The pump provides
fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator, located in the fuel tank, maintains the correct fuel
pressure to the fuel injection system. A separate pipe returns unused fuel to the fuel tank.
Circuit/System Verification
Important:
*
Inspect the fuel system for damage or external leaks before proceeding.
*
Verify that adequate fuel is in the fuel tank before proceeding.
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The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
*
Before proceeding with this test, review the User Manual CH 48027-5 for Safety Information and Instruction.
1. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. You should hear the fuel pump turn ON and OFF.
^
If the fuel pump does not operate, refer to Fuel Pump Electrical Circuit Diagnosis. See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics
2. Ignition OFF, all accessories OFF, install a CH-48027. Refer to Fuel Pressure Gage Installation and Removal.
3. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. Verify the fuel pressure is between 345-414 kPa (50-60 psi) and
does not decrease more than 34 kPa (5 psi) in 1 minute.
Circuit/System Testing
Important:
*
The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
*
DO NOT start the engine.
Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool and observe the fuel pressure gage while the fuel pump is operating.
Verify the fuel pressure is between 345-414 kPa (50-60 psi).
^
If the fuel pressure is greater than the specified range, test for a restriction in the return side of the fuel filter. If the fuel filter tests normal,
replace the fuel pump module.
^
If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below. If all items test normal, replace the fuel
pump module.
*
Restricted fuel feed pipe
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Restricted or plugged fuel filter
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Restricted or plugged strainer
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Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
2. Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute.
