Symptom Chart

SYMPTOM	POSSIBLE CAUSES	ACTION
Engine cranks, but does not fire	Low/contaminated fuel Engine breather system disconnected/restricted Ignition system Fuel leak Blocked fuel filter Fuel pump module fault Crankshaft Position (CKP) Sensor Engine Control Module (ECM) fault	Check the fuel level/condition Check the engine breather system Check for ignition system DTCs Check the fuel system for leaks/damage Check the fuel filter for a blockage/restriction Check the fuel pump module operation Check the CKP sensor
Engine cranks and fires, but will not start	Evaporative emissions purge valve Low fuel pressure Fuel leak Blocked fuel filter Fuel pump module fault Spark plugs HT short to ground (tracking) check rubber boots for cracks/damage Ignition coil failure(s) Harness	Check the evaporative emissions purge valve Check the fuel pressure Check the fuel system for leaks/damage Check the fuel filter for a blockage/restriction Check the fuel pump module operation Check the spark plugs and ignition coils
Difficult to start after hot soak (vehicle standing after engine has reached operating temperature)	Injector leak Fuel temperature sensor Intake Air Temperature (IAT) sensor Mass Air Flow (MAF) sensor Evaporative emissions purge valve Fuel pump module fault Ignition system	Check the fuel injectors Check the fuel temperature sensor, check the IAT and MAF sensor circuits Check the evaporative emissions purge valve Check the operation of the fuel pump module Check the spark plugs and ignition coil circuits
Engine stalls soon after start	Breather system disconnected/restricted ECM relay Harness MAF sensor Ignition system Air cleaner restricted Air leakage Fuel lines Fuel rail pressure (FRP) sensor	Check the engine breather system Check the ECM relay and circuits Check the MAF sensor circuits Check the spark plugs and ignition coil circuits Check for a restricted air cleaner Check the intake air system for leaks Check the fuel lines for leaks/damage Check the FRP sensor circuits
Engine hesitates/poor acceleration	Restricted pedal travel (carpet, etc) Ignition system Air leakage Heated oxygen (HO2) sensors Fuel pressure Blocked fuel filter Fuel lines Fuel pump module fault Injector leak Throttle position (TP) sensors Throttle motor Accelerator pedal position (APP) sensor Transmission malfunction	Check the accelerator pedal travel Check the spark plugs and ignition coil circuits Check the intake air system for leaks Check the HO2 sensor circuits Check the fuel pressure Check the fuel filter for a blockage/restriction Check the fuel system for leaks/damage Check the fuel pump module operation Check the fuel injectors Check the TP sensor, throttle motor and APP sensor circuits
Engine backfires	Ignition system Air leakage Fuel lines Fuel pump module fault MAF sensor HO2 sensors APP sensor	Check the spark plugs and ignition coil circuits Check the intake air system for leaks Check the fuel system for leaks/damage Check the fuel pump module operation Check the MAF, HO2 and APP sensor circuits
Engine surges	Fuel lines Fuel pump module fault MAF sensor Harness TP sensors Throttle motor Ignition system Engine Control Module (ECM) fault	Check the fuel system for leaks/damage Check the fuel pump module operation Check the MAF sensor, TP sensor and throttle motor circuits Check the ignition coil circuits
Engine detonates/knocks	Fuel quality Fuel lines Fuel pump module fault Air leakage FRP sensor Knock sensor (KS)/circuit malfunction MAF sensor HO2 sensors Barometric sensor malfunction (internal Engine Control Module (ECM) fault)	Check the fuel for contamination/grade/quality Check the fuel system for leaks/damage Check the fuel pump module operation Check the intake air system for leaks Check the FRP, KS, MAF and HO2 sensor circuits
Fuel gauge reading empty with fuel in the fuel tank	Active fuel level sensor circuit open circuit Passive fuel level sensor circuit open circuit Instrument cluster internal failure	Using the manufacturer approved diagnostic system, perform the guided diagnostic routine - Fuel Level Sensor Test
Fuel gauge not reading empty with no fuel in the fuel tank	Jet pump fault Fuel crossover tube blocked or leaking	Using the manufacturer approved diagnostic system, check datalogger signals - Fuel Level Sensor "pump/active/A" (0xD908) - Fuel Level Sensor "eject/passive/B" (0xD907). Refer to the table below. If the right sensor reads empty when the left sensor reads more than empty, check that the jet pump is transferring fuel from the left side to the right side