Evaporative Emissions System: Testing and Inspection

RESULTS OF INCORRECT OPERATION
Poor idle, stalling and poor driveability can be caused by the following items:

- Inoperative EVAP canister purge valve.
- Damaged EVAP canister.
- Hoses split, cracked and, or not connected to the proper tubes.

Evidence of fuel loss or fuel vapor odor can be caused by the following items:

- Liquid fuel leaking from fuel lines, or fuel pump.
- Cracked or damaged EVAP canister.
- Disconnected, mis-routed, kinked, deteriorated or damaged vapor hoses, or control hoses.

If the EVAP canister purge valve is always open, the canister can purge to the intake manifold at all times. This can allow extra fuel during warm-up, which can cause a too rich operation.

If the EVAP canister purge valve is always closed, the canister can become over-loaded, resulting in fuel odor.