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Alfa Romeo 147 Factory Service Manual (2000-2004)22 · Fault diagnosis

22 · Diagnostics

Lean fuel system

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2004
Section: Examiner › Lean fuel system

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Fault diagnosisLean fuel system

LEAN FUEL SYSTEM

1.6 TS, 2.0 TS

1	INTAKE AND EXHAUST SYSTEM LEAKAGE CHECK	All OK	Problems met	Operation
		Results of the tests
	Check the intake and exhaust system visually and by listening, to check that there are no leaks downstream of the MAP sensor/flow meter. Also take into account: blow-by circuit; canister circuit, checking that the valve is not stuck open; brake servo vacuum pipes; Injector O-Rings	Continue to Step 2	There are leaks	Eliminate leaks from the system. Replace faulty parts if necessary Continue to Step 5
2	PETROL PRESSURE CHECK	All OK	Problems met	Operation
	Turn the key to MAR and check that fuel pump activates. Whilst the pump is activated, check that the fuel pressure is not too low	Continue to Step 3	Low pressure: fuel filter blocked/obstructed	Replace the fuel pupm Op. 1056A70 Continue to Step 5
			Low pressure: supply pipe restrictions/leaks	Renew or, if necessary, replace the pipes involved
			Low pressure: pressure regulator defective	Replace the fuel pupm Op. 1056A70 Continue to Step 5
			Low pressure: pressure regulator incorrectly calibrated	Replace the fuel pupm Op. 1056A70 Continue to Step 5
			Low pressure: electrical problem in the fuel pump	Restore the correct connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENTIf necessary replace the fuel pump Continue to Step 5
			Low pressure: excess pressure valve stuck open	Replace the fuel pupm Op. 1056A70 Continue to Step 5
3	FUEL QUALITY CHECK	All OK	Problems met	Operation
	Check that there is no water or other substances in the tank which is contaminating the fuel.	Continue to Step 4	Impurities present	Clean the tank Op. 1040A24and introduce new fuel. Continue to Step 5
4	UPSTREAM LAMBDA SENSOR CHECK	All OK	Problems met	Operation
	Starting from Step 3 See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL ERROR			Search for the fault starting from another symptom'
5	ERROR CANCELLING AND CHECKING	All OK	Problems met	Operation
	Use a tester to cancel the errors in the control unit. Road test the vehicle and check that the error does not occur again	Continue to Step 6	The fault persists	Continue to Step 1
6	CORRECT OPERATION CHECK	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists	Search for the fault starting from another symptom'

3.2 V6

1	INTAKE AND EXHAUST SYSTEM LEAKAGE CHECK	All OK	Problems met	Operation
		Results of the tests
	Check the intake and exhaust system visually and by listening, to check that there are no leaks downstream of the MAP sensor/flow meter. Also take into account: blow-by circuit; canister circuit, checking that the valve is not stuck open; brake servo vacuum pipes; Injector O-Rings	Continue to Step 2	There are leaks	Eliminate leaks from the system. Replace faulty parts if necessary Continue to Step 5
2	PETROL PRESSURE CHECK	All OK	Problems met	Operation
	Turn the key to MAR and check that fuel pump activates. Whilst the pump is activated, check that the fuel pressure is not too low	Continue to Step 3	Low pressure: fuel filter blocked/obstructed	Replace the fuel pupm Op. 1040A70 Continue to Step 5
			Low pressure: supply pipe restrictions/leaks	Renew or, if necessary, replace the pipes involved
			Low pressure: pressure regulator defective	Replace the fuel pupm Op. 1040A70 Continue to Step 5
			Low pressure: pressure regulator incorrectly calibrated	Replace the fuel pupm Op. 1040A70 Continue to Step 5
			Low pressure: electrical problem in the fuel pump	Restore the correct connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENTIf necessary replace the fuel pump Op. 1040A70 Continue to Step 5
			Low pressure: excess pressure valve stuck open	Replace the fuel pupm Op. 1040A70 Continue to Step 5
3	FUEL QUALITY CHECK	All OK	Problems met	Operation
	Check that there is no water or other substances in the tank which is contaminating the fuel.	Continue to Step 4	Impurities present	Clean the tank Op. 1040A24and introduce new fuel. Continue to Step 5
4	UPSTREAM LAMBDA SENSOR CHECK	All OK	Problems met	Operation
	Continue as instructed in the Table See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL ERRORstarting from Step 3	End of diagnosis
5	ERROR CANCELLING AND CHECKING	All OK	Problems met	Operation
	Use a tester to cancel the errors in the control unit. Road test the vehicle and check that the error does not occur again	Continue to Step 6	The fault persists	Continue to Step 0
6	CORRECT OPERATION CHECK	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis

‹ Prev Rich fuel system Next › Misfire error

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