Test Procedure

HC1 DTC P0148 OR SYMPTOMS WITHOUT DTCS: CHECK THE SYSTEM INTEGRITY

Visually inspect the complete fuel delivery system for damage and leakage.
Check the following:
- fuel lines and connections
- relays
- fuel tank
- fuel pump
- fuel pressure regulator
- fuel pulse damper
- fuel rail at injectors
- damaged connector pins
- electrical connectors not fully engaged
Verify the vehicle has followed the maintenance schedule. A new fuel filter should have been installed within the last 48,280 km (30,000 miles).
Verify the inertia fuel shutoff (IFS) switch is set (button pushed in). Refer to the Owner's Literature for location.
Verify the fuse integrity.
Verify the battery is fully charged.
Verify clean sufficient fuel.

Is a concern present?

Yes	No
REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.	GO to HC2.

HC2 CHECK ALL SYSTEM RELATED DEVICES (SENSOR, DAMPER OR REGULATOR) FOR LEAKAGE

Key in OFF position.
FP connector connected.
Remove the vacuum hose on each system device connected to the fuel rail.
Inspect for the presence of fuel in the vacuum line of each device connected to the fuel rail.
Key ON, engine running.
Check for manifold vacuum at each system related component with a vacuum line.
Key in OFF position.

Are all vacuum lines for system related devices indicating no fuel present?

Yes	No
GO to HC3.	If the vacuum line connected to a component indicates that a fuel leak is present, INSTALL a new component. CLEAR the DTCs. REPEAT the self-test.

HC3 CHECK THE FUEL PRESSURE

Key in OFF position.
Relieve the fuel pressure. Refer to the appropriate FUEL SYSTEM - GENERAL INFORMATION article for the Fuel System Pressure Release procedure.
Mechanical fuel pressure gauge connected.
Key ON, engine OFF.
Pressurize the fuel system. Refer to the appropriate FUEL SYSTEM - GENERAL INFORMATION article for the Fuel System Pressure Release procedure to pressurize the fuel system.
FP connector connected.
Cycle the key several times to charge the fuel system.
Compare the fuel pressure reading to the Fuel System Specification Chart.

Is the fuel pressure within range?

Yes	No
GO to HC6.	GO to HC4.

HC4 CHECK THE FUEL PUMP GROUND CIRCUIT FOR AN OPEN IN THE HARNESS

NOTE: Refer to the appropriate SYSTEM WIRING DIAGRAMS for schematic and connector information.

FP connector disconnected.

Measure the voltage between:

( + ) Vehicle Battery	( - ) FP Connector, Harness Side
Positive terminal	FPGND

Is the voltage greater than 10 V?

Yes	No
GO to HC5.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

HC5 CHECK THE FUEL PUMP POWER CIRCUIT FOR AN OPEN IN THE HARNESS

NOTE: During output state control, the fuel pump stays commanded on for only about 5 seconds.

Verify the inertia fuel shutoff (IFS) switch is set (button pushed in). Refer to the Owner's Literature for location.
FP connector disconnected.
Key ON, engine OFF.
Access the PCM and control the FP PID.
Be aware that output state control turns off the FP after a calibrated time. If this happens, command the outputs on again to continue testing.

Measure the voltage between:

( + ) FP Connector, Harness Side	( - ) Vehicle Battery
FPPWR	Negative terminal

Is the voltage greater than 10 V?

Yes	No
GO to HC6.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

HC6 CHECK THE FUEL PRESSURE LEAKDOWN

NOTE: When the fuel pump is commanded off, the fuel pressure may substantially decrease and then stabilize.

NOTE: During output state control, the fuel pump stays commanded on for only about 5 seconds.

Mechanical fuel pressure gauge connected.
Key ON, engine OFF.
Access the PCM and control the FP PID.
Run the fuel pump to obtain maximum fuel pressure.
Command the fuel pump off.
Allow the fuel pressure to stabilize.
Record the stabilized reading.
Monitor the fuel pressure for 1 minute.

Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading (MRFS) or greater than 275 kPa (40 psi) (ERFS) after 1 minute?

Yes	No
For ERFS, GO to HC8. For MRFS, GO to HC9.	GO to HC7.

HC7 CHECK THE FUEL INJECTOR FLOW AND LEAKAGE

NOTE: Observe the Warnings, Cautions, and Notes.

Check the fuel injectors for leakage and flow rate using the injector flow tester or other method such as inspecting the intake manifold for fuel.

Are the test results satisfactory?

Yes	No
For ERFS, GO to HC8. For MRFS, GO to HC9.	INSTALL a new fuel injector as necessary. REFER to the appropriate FUEL CHARGING & CONTROLS article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.

HC8 COMPARE THE FRP PID TO THE MECHANICAL GAUGE

NOTE: Most mechanical gauges are referenced to atmospheric pressure. The FRP sensor is referenced to manifold pressure. In order to make a valid comparison, the engine must be off.

NOTE: The vehicle may exhibit a long crank until the fuel system is pressurized.

Key in OFF position.
Relieve the fuel pressure. Refer to the appropriate FUEL SYSTEM - GENERAL INFORMATION article for the Fuel System Pressure Release procedure.
Disable the fuel pump.
Key ON, engine OFF.
Monitor the mechanical gauge.
Access the PCM and monitor the FRP PID.
Compare the FRP PID value to the mechanical gauge.
Key in OFF position.
Pressurize the fuel system. Refer to the appropriate FUEL SYSTEM - GENERAL INFORMATION article for the Fuel System Pressure Release procedure to pressurize the fuel system.
Key ON, engine running.
Allow the fuel pressure to stabilize.
Key in OFF position.
Key ON, engine OFF.
Compare the FRP PID value to the mechanical gauge.

Are the FRP PID values within 34 kPa (5 psi) of the mechanical gauge readings?

Yes	No
GO to HC9.	INSTALL a new FRP sensor. REFER to the fuel system WARNING information at the beginning of this pinpoint test. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

HC9 MONITOR THE FUEL PRESSURE WHILE ROAD TESTING THE VEHICLE

WARNING: STRICT OBSERVANCE OF POSTED SPEED LIMITS AND ATTENTION TO DRIVING CONDITIONS ARE MANDATORY WHEN CARRYING OUT THE ROAD TEST. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.

NOTE: Some concerns may only be present during certain fuel level conditions. Determine the fuel level at the time of the concern. Access the information from the customer information worksheet and the customer.

Key in OFF position.
Securely route the mechanical gauge so that the gauge is viewable while road testing the vehicle.
Key ON, engine running.
Engine at normal operating temperature.
Monitor the mechanical gauge.
From a stop, accelerate to 89 km/h (55 mph) at full throttle. Repeat this 3 times.

Is the fuel pressure always greater than 240 kPa (35 psi)?

Yes	No
For symptoms without DTCs, the concern is elsewhere. RETURN to STEP 2: NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX for further direction. For all others, unable to duplicate or identify the concern at this time.	GO to HC10.

HC10 CHECK THE FUEL SUPPLY LINE FOR RESTRICTION

NOTE: Observe the Warnings, Cautions, and Notes.

Key in OFF position.
Disconnect the fuel supply line at the fuel rail.
Disconnect the fuel supply line at the fuel pump.
Check the fuel supply line for restriction.
Apply 21 to 34 kPa (3 to 5 psi) air pressure to the fuel supply line.

Does air flow freely through the line?

Yes	No
INSTALL a new Fuel Filter assembly. REFER to the appropriate FUEL TANK AND LINES article .	REPAIR the cause of the restriction.
GO to HC11.	CLEAR the DTCs. REPEAT the self-test.

HC11 VERIFY THE REPAIR

Key ON, engine running.
Engine at normal operating temperature.
Monitor the mechanical gauge.
From a stop, accelerate to 89 km/h (55 mph) at full throttle. Repeat this 3 times.

Is the fuel pressure always greater than 240 kPa (35 psi)?

Yes	No
The test is complete and no concerns are present.	INSTALL a new FP module. REFER to the appropriate FUEL TANK AND LINES article . CLEAR the DTCs. REPEAT the self-test.