TROUBLESHOOTING GUIDE

F-55prose procedure

Troubleshooting Guide (steps 6–11)

STEP	INSPECTION	RESULT	ACTION
6	Check for correct intake manifold vacuum Vacuum: More than about 450 mmHg (17.7 inHg)	Yes	Go to next step
6	Check for correct intake manifold vacuum Vacuum: More than about 450 mmHg (17.7 inHg)	No	Check for air leakage of intake air system components (page F-93)
7	Check if air cleaner element is clean (page F-75)	Yes	Go to next step
7	Check if air cleaner element is clean (page F-75)	No	Replace air cleaner element (page F-92)
8	Check for correct ignition timing at idle (page F-75) Ignition timing: 10° ± 1° BTDC	Yes	Check if ignition timing advances when accelerating - If advances, go to next step - If no advance, replace ECU (page F-127)
8	Check for correct ignition timing at idle (page F-75) Ignition timing: 10° ± 1° BTDC	No	Adjust (page F-75)
9	Check for correct fuel line pressure at idle (page F-103) Fuel line pressure: 265—314 kPa (2.7—3.2 kg/cm², 38—46 psi) (Vacuum hose to pressure regulator disconnected)	Yes	Check if fuel line pressure decreases when accelerating quickly - If decreases, check fuel line and filter for clogging - If no decrease, go to next step
9	Check for correct fuel line pressure at idle (page F-103) Fuel line pressure: 265—314 kPa (2.7—3.2 kg/cm², 38—46 psi) (Vacuum hose to pressure regulator disconnected)	No	Low pressure Check for fuel line pressure while pinching fuel return hose - If fuel line pressure quickly increases, check pressure regulator (page F-111) - If fuel line pressure gradually increases, check for clogging between fuel pump and pressure regulator - If not clogged, check fuel pump maximum pressure (page F-108)
10	Check if exhaust system is restricted (page F-115)	Yes	Repair or replace (page F-115)
10	Check if exhaust system is restricted (page F-115)	No	Go to next step
11	Try known good ECU and check if condition improves (page F-127)

INSPECTIONCheck for correct intake manifold vacuum Vacuum: More than about 450 mmHg (17.7 inHg)

RESULTYes

ACTIONGo to next step

INSPECTIONCheck for correct intake manifold vacuum Vacuum: More than about 450 mmHg (17.7 inHg)

RESULTNo

ACTIONCheck for air leakage of intake air system components (page F-93)

INSPECTIONCheck if air cleaner element is clean (page F-75)

RESULTYes

ACTIONGo to next step

INSPECTIONCheck if air cleaner element is clean (page F-75)

RESULTNo

ACTIONReplace air cleaner element (page F-92)

INSPECTIONCheck for correct ignition timing at idle (page F-75) Ignition timing: 10° ± 1° BTDC

RESULTYes

ACTIONCheck if ignition timing advances when accelerating - If advances, go to next step - If no advance, replace ECU (page F-127)

INSPECTIONCheck for correct ignition timing at idle (page F-75) Ignition timing: 10° ± 1° BTDC

RESULTNo

ACTIONAdjust (page F-75)

INSPECTIONCheck for correct fuel line pressure at idle (page F-103) Fuel line pressure: 265—314 kPa (2.7—3.2 kg/cm², 38—46 psi) (Vacuum hose to pressure regulator disconnected)

RESULTYes

ACTIONCheck if fuel line pressure decreases when accelerating quickly - If decreases, check fuel line and filter for clogging - If no decrease, go to next step

INSPECTIONCheck for correct fuel line pressure at idle (page F-103) Fuel line pressure: 265—314 kPa (2.7—3.2 kg/cm², 38—46 psi) (Vacuum hose to pressure regulator disconnected)

RESULTNo

ACTIONLow pressure Check for fuel line pressure while pinching fuel return hose - If fuel line pressure quickly increases, check pressure regulator (page F-111) - If fuel line pressure gradually increases, check for clogging between fuel pump and pressure regulator - If not clogged, check fuel pump maximum pressure (page F-108)

INSPECTIONCheck if exhaust system is restricted (page F-115)

RESULTYes

ACTIONRepair or replace (page F-115)

INSPECTIONCheck if exhaust system is restricted (page F-115)

RESULTNo

ACTIONGo to next step

INSPECTIONTry known good ECU and check if condition improves (page F-127)

RESULT

ACTION

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TROUBLESHOOTING GUIDE

Troubleshooting Guide (steps 6–11)

See also

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