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Mazda CX-9 Grand Touring. Manual - part 242

DTC P0148 [MZI-3.7]

DTC P0148 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES

DIAGNOSTIC PROCEDURE

DTC P0148 (MZI-3.7) DIAGNOSTIC PROCEDURE

are reconnected.



Turn the ignition switch to the ON
position (Engine off).



Clear the DTC from the PCM memory
using the M-MDS.



Retrieve DTCs using the M-MDS.



Is the PENDING CODE for this DTC
present?

3.7] .)

Go to the next step.

VERIFY AFTER REPAIR PROCEDURE



Perform "AFTER REPAIR
PROCEDURE". (See AFTER
REPAIR PROCEDURE [MZI-3.7].)



Are any DTC present?

Yes

Go to the applicable DTC inspection. (See
DTC TABLE [MZI-3.7].)

Troubleshooting completed.

DTC P0148

Fuel delivery error

DETECTION CONDITION



At least 1 bank is lean at wide open throttle (WOT).

POSSIBLE CAUSE



Severely restricted fuel filter



Severely restricted fuel supply line



Damaged or worn fuel pump



Damaged or contaminated MAF sensor

STEP

INSPECTION

ACTION

VERIFY FREEZE FRAME DATA HAS
BEEN RECORDED



Has FREEZE FRAME DATA been
recorded?

Yes Go to the next step.

Record FREEZE FRAME DATA on the repair

order, then go to the next step.

VERIFY RELATED REPAIR
INFORMATION AVAILABILITY



Verify related Service Bulletins and/or
on-line repair information availability.



Is any related Service Bulletins
available?

Yes

Perform repair or diagnosis according to the
available Service Bulletins.



If the vehicle is not repaired, go to the
next step.

Go to the next step.

INSPECT SYSTEM INTEGRITY

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:08:35 AM

Page 101



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 fuel injectors



Damaged connector pins



Electrical connectors not fully
engaged



Verify that the vehicle has followed the
maintenance schedule. A new fuel filter
should have been installed within the
last 48,280 km {29,934 mph}.



Verify that the fuse integrity.



Verify that the battery is fully charged.



Verify that there is clean sufficient fuel.



Is a concern present?

Yes Repair if necessary. Then go to Step 11.

Go to the next step.

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



Turn the ignition switch off.



Connect the fuel pump connector.



Turn the ignition switch to the ON
position (Engine running)



Check for manifold vacuum at each
system related component with a
vacuum line.



Turn the ignition switch off.



Wait 10 s.



Turn the ignition switch to the ON
position (Engine running)



Run the engine for approx. 10 s.



Turn the ignition switch off.



Remove the vacuum hose on each

Yes Go to the next step.

If the vacuum line connected to a component

indicates that a fuel leak is present, install a

new component. Then go to Step 11.

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:08:35 AM

Page 102

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.



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

INSPECT FUEL PRESSURE



Turn the ignition switch off.



Relieve the fuel pressure. Refer to the .



Connect the mechanical fuel pressure
gauge.



Turn the ignition switch to the ON
position (Engine off)



Pressurize the fuel system. Refer to the
for the Fuel System Pressure Release
procedure to pressurize the fuel system.



Compare the fuel pressure reading to
the Fuel System Specification Chart.



Is the fuel pressure within range?

Yes Go to Step 9.

Go to the next step.

INSPECT FUEL PUMP GROUND
CIRCUIT FOR OPEN CIRCUIT IN
WIRING HARNESS



Disconnect the fuel pump connector.



Measure the resistance between fuel
pump connector terminal D (wiring
harness-side) and body ground.



Is the voltage less than 0.5 ohm?

NOTE:



Refer to the for schematic and
connector information.

Yes Go to the next step.

Repair or replace suspected part, Then go to

Step 11.

INSPECT FUEL PUMP POWER SUPPLY
CIRCUIT FOR OPEN CIRCUIT IN
WIRING HARNESS



Disconnect the fuel pump connector.



Turn the ignition switch to the ON
position (Engine off)



Access the PCM and control the FP
PID.

Yes Go to the next step.

Repair or replace suspected part, Then go to

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:08:35 AM

Page 103



Measure the voltage between fuel pump
connector terminal B (wiring harness-
side) and body ground.



Is the voltage more than 10 V?

Step 11.

INSPECT FUEL PRESSURE LEAK



Connect the mechanical fuel pressure
gauge.



Turn the ignition switch to the ON
position (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 min.



Does the fuel pressure remain within 34
kPa {255 mmHg, 10.0 inHg} of the
recorded reading after 1 min?

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
approx. 5 s.

Yes Perform the KOEO self-test. Go to Step 10.

Go to the next step.

INSPECT FUEL INJECTOR
OPERATION



Remove the fuel injector.



Inspect the fuel injector operation.



Is the fuel injector normal?

Yes Go to the next step.

Replace the fuel injector, then go to Step 11.

INSPECT FUEL SUPPLY LINE FOR
RESTRICTION

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:08:35 AM

Page 104

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