22 · Diagnostics

Lean fuel system

Make: Fiat
Model: Doblò Factory Service Manual
Year: 2000–2010
Section: Examiner › Lean fuel system

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Fault diagnosisLean fuel system

LEAN FUEL SYSTEM

1	INTAKE AND EXHAUST SYSTEM LEAKAGE CHECK	All OK	Problems met	Operation
		Results of the tests
	Check the intake and exhaust system, checking that there are no leakd downstream of the MAP sensor/flow meter. See Test 1072A 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	Leaks are present	Eliminate leaks from the system. Replace faulty parts if necessary Continue to Step 6
2	PETROL PRESSURE CHECK	All OK	Problems met	Operation
	Turn the key to MAR and check fuel pump activates. While the pump is active, check fuel pressure is not too low	Continue to Step 3	Low pressure: fuel filter blocked/obstructed	Replace the fuel pump Op. 1070A40 Continue to Step 6
			Low pressure: supply pipe restrictions/leaks	Renew or, if necessary, replace the pipes involved
			Low pressure: pressure regulator defective	Replace the fuel pump Op. 1070A40 Continue to Step 6
			Low pressure: pressure regulator incorrectly calibrated	Calibrate correctly. Continue to Step 6
			Low pressure: electrical problem in the fuel pump	Restore correct connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENTIf necessary, replace the fuel pump Continue to Step 6
			Low pressure: excess pressure valve stuck open	Replace the fuel pump Op. 1040A70 Continue to Step 6
3	CHECK ON FUEL INJECTORS	All OK	Problems met	Operation
	Check the mechanical seal of the injectors. In particular, check that none of the injectors are stuck closed	Continue to Step 4	Injectors defective	Renew the correct seal for the injectors, if necessary replace them Op. 1056B70 Continue to Step 6
4	CHECKING FUEL QUALITY	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 5	Impurities are present	Clean the tank Op. 1040A10and introduce new fuel. Continue to Step 6
5	UPSTREAM LAMBDA SENSOR CHECK	All OK	Problems met	Operation
	Starting from Step 3 See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL ERROR	End of diagnosis
6	DELETING AND CHECKING ERROR	All OK	Problems met	Operation
	Use a tester to cancel the errors in the control unit.	End of diagnosis	Carry out a road test and ensure the error does not recur	Continue to Step 7
	Use a tester to cancel the errors in the control unit.	End of diagnosis	The fault persists	Continue as instructed in the Table Z50
7	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists

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	Leaks are present	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 fuel pump activates. While the pump is active, check fuel pressure is not too low	Continue to Step 3	Low pressure: fuel filter blocked/obstructed	Replace the fuel pump Op. 1070A40 Continue to Step 6
			Low pressure: fuel filter blocked/obstructed	Replace the fuel pump 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 pump Op. 1040A70 Continue to Step 5
			Low pressure: pressure regulator incorrectly calibrated	Replace the fuel pump Op. 1040A70 Continue to Step 5
			Low pressure: electrical problem in the fuel pump	Restore 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 pump Op. 1040A70 Continue to Step 5
3	CHECKING FUEL QUALITY	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 are present	Clean the tank Op. 1040A24and introduce new fuel. Continue to Step 5
4	UPSTREAM LAMBDA SENSOR CHECK	All OK	Problems met	Operation
	Continue according to the instructions for the See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL ERROR	Continue to Step 3
5	DELETING AND CHECKING ERROR	All OK	Problems met	Operation
	Use a tester to cancel the errors in the control unit. Carry out a road test and ensure the error does not recur	Continue to Step 6	The fault persists	Continue to Step 0
6	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists

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Parts & tools for this job Staging For 2000 Fiat Doblò

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