Difficult To Start

NOTE: If engine cranks but will not run, see appropriate ENGINE CRANKS BUT WILL NOT RUN testing in BASIC DIAGNOSTIC PROCEDURES article.

Perform On-Board Diagnostic II System Check.
Perform Electronic Throttle Control (ETC) System Check.
Check for blown fuel or ignition system fuses.
Check for contaminated fuel.
Check fuel pressure.
Visually inspect injector fuse(s).
Check for faulty Engine Coolant Temperature (ECT) sensor and circuit.
Check for faulty Intake Air Temperature (IAT) sensor and compare readings with ECT sensor.
Check for loss of crank signal to PCM.
Check EGR system.
Check fuel pump relay and circuits.
Check ignition system and grounds.
Check for shorts by spraying plug wires with a fine mist of water.
Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits.
Check for faulty Idle Air Control (IAC) operation (if equipped).
Check for faulty main (or PCM) relay.
Check for faulty Throttle Position (TP) sensor.
Check for faulty PCV system.
Check for faulty Camshaft Position (CMP) sensor.
Check Manifold Absolute Pressure (MAP) or Mass Air Flow (MAF) sensor.
Ensure the installed PROM and/or PCM is correct for that particular vehicle. Check with dealer for latest application information.
Check for improper or worn camshaft.
Check engine compression.
Check for leaking cylinder head gasket.
Check fuel injectors drain down time and circuit.
Check for intake and exhaust manifold leaks.