Difficult To Start/No Start (Cranks Okay)

Check for vacuum leaks (oil filler cap, oil dipstick, hose connections, PCV hose and valve, etc.).
Verify secondary ignition system performance.
Ensure ignition timing is correct.
Check cam position sensor (if equipped).
Ensure fuel system performs properly (pump, lines, filter, pressure regulator and cold start injector).
Check circuit opening relay.
Check fuel pump switch in airflow meter (if equipped).
If engine starts with accelerator pedal depressed, check idle speed control valve (if equipped) and wiring connection.
Check auxiliary air valve (if equipped).
Check wiring connection to ECU.
Check power to ECU via fusible links, fuses and EFI main relay.
Check airflow meter, coolant temperature sensor and air temperature sensor.
Check engine compression and valve clearance.
Check injection signal circuit.
Check timing belt.