Evaporative Emissions: Description
| EVAP SYSTEM COMPONENTS | |
|---|---|
| CALLOUT | DESCRIPTION |
| 1 | Filter - Fresh Air Inlet |
| 2 | Filter Hose (Filter to ESIM) |
| 3 | Evaporative System Integrity Monitor (ESIM) |
| 4 | Evaporative Canister |
| 5 | Gas Cap or Cap-less Refueling Unit (if equipped) |
| 6 | Recirculation Tube (metal portion) (FTPS to Fuel Filler Tube) |
| 7 | Fuel Filler Tube |
| 8 | Fuel Tank Pressure Sensor (FTPS) |
| 9 | Grade Vent Valve (GVV) |
| 10 | Hose - Fuel Filler Tube to ICV |
| 11 | Inlet Check Valve (ICV) |
| 12 | GVV Tube (GVV to MFCV) |
| 13 | Recirculation Tube (Fuel Tank to FTPS) |
| 14 | Canister Tube (Fuel Tank to Canister) |
| 15 | Multi-Function Control Valve (MFCV) in the Fuel Delivery Flange |
| 16 | Fuel Tank |
| 17 | Purge Tube (Purge Solenoid to Canister) |
| 18 | Purge Control Valve Tee |
| 19 | Purge Control Valve |
| 20 | Purge Control Valve Filter |
| 21 | Purge Solenoid |
| 22 | Evaporative System Turbocharger Tee |
| 23 | Check Valve (to the Turbocharger) |
| 24 | Check Valve (to the Manifold) |
| 25 | Ejector Tee (Venturi) |
| 26 | Hose to the Airbox Side of the Turbocharger |
| 27 | Hose to the Charge Air Cooler Side of the Turbocharger |
| 28 | Manifold Hose (Purge Solenoid to Engine Manifold) |
The evaporative emissions system is designed to control the release of fuel vapors into the atmosphere. The Multi-Function Control Valve (15) and Grade Vent Valve (9) are used to reduce emissions due to the venting of vapor expansion within the Fuel Tank (16). When fuel evaporates from the fuel tank, vapors pass through the Canister Tube (14) to the Evaporative Charcoal Canister (4) where they are temporarily held. When the engine is running, the vapors are drawn into the intake manifold through the Purge Tube (17). In addition, fuel vapors produced during vehicle refueling are allowed to pass through the Recirculation Tube (6) to the Evaporative Charcoal Canister (4) for temporary storage (prior to being drawn into the intake manifold). The Multi-Function Control Valve (15) and Grade Vent Valve (9) are non-serviceable components of the fuel tank assembly. The system is equipped with self-diagnosing capability using an Evaporative System Integrity Monitor (3). Refer to SWITCH, EVAPORATIVE EMISSIONS SYSTEM MONITOR, OPERATION .
The Fuel Tank Pressure Sensor (8) provides the PCM with information on vapor pressure inside the fuel tank. Excessive fuel tank pressure could cause fuel vapors to vent out the fuel filler cap or damage system components while insufficient fuel tank pressure (vacuum) caused by lack of fresh air entering the tank to take the place of consumed fuel, could lead to a collapsed tank, lines or loss of fuel pressure.
The Inlet Check Valve (11) prevents fuel from splashing back on the customer during vehicle refueling. This valve is also a non-serviceable component of the fuel tank assembly.
The intake manifold of the turbocharged engine sometimes operates with a positive pressure. This pressurized airflow must not be allowed to backflow into the Evaporative Charcoal Canister (4). When the engine is equipped with a turbocharger, the Purge Control Valve (19) is used to relieve vacuum during boost. One-way check valves (23 and 24) prevent pressurized airflow into the EVAP Purge Solenoid (21).