Fuel Delivery and Air Induction: Testing and Inspection

NOTE: Refer to TECHNICAL SERVICE BULLETINS for possible modifications and tips concerning fuel systems.
Check for fault codes. Refer to COMPUTERS AND CONTROL SYSTEMS.
Possible causes for symptoms are listed in order of testing priority.

ENGINE CRANKS BUT WILL NOT START

^ Air leaks at the induction system
^ Fuel tank is empty
^ Fuel pump relay defective
^ ECU main relay defective
^ Fuel filter restricted
^ Poor quality fuel or contaminated fuel
^ Fuel supply lines damaged or misrouted
^ Fuel pressure regulator defective
^ Fuel pump defective
^ Fuel injectors defective or clogged
^ ECU defective

ENGINE STARTS BUT RUNS ROUGH AND DIES

^ Air leaks at the induction system
^ Air leaks at the crankcase
^ Fuel filter restricted
^ Poor quality fuel or contaminated fuel
^ Fuel supply lines damaged or misrouted
^ Fuel pump defective (insufficient output)
^ Fuel pressure regulator defective
^ Carbon on intake valves
^ Fuel injectors defective or clogged
^ ECU defective

ENGINE RUNS ROUGH, STUMBLES OR HESITATES ON ACCELERATION

^ Air leaks at the induction system
^ Air leaks at the crankcase
^ Fuel filter restricted
^ Poor quality fuel or contaminated fuel
^ Fuel supply lines damaged or misrouted
^ Carbon on intake valves
^ Defective fuel injectors (poor spray pattern, clogged or leaking)
^ Fuel pump defective (insufficient output)
^ Fuel pressure regulator defective
^ ECU defective


ENGINE RUNNING ON (IGNITION OFF)

^ Fuel injectors leaking