Evaporative Emission Systems 4-CYL: Overview Saab 9-3 II

Scheme 413

Scheme 414

1. Check that the pressure tester is in good condition and not leaking.
2. Check that the filler cap is on tight.
3. Connect pressure tester J41413 to the service port at the purge valve in the engine compartment. NOTE: Do not fit the pressure tester adapter to the filler cap connection, as this would prevent the filler cap from sealing in its correct position.
4. Activate the EVAP canister cut-off valve using the diagnostic tool. Select the "ACTIVATE" menu. Select "TANK BLEEDING OFF/ON". Select "ON"
5. Pressurize the system and perform the pressure test, following the instructions in the Kent - Moore manual.

Scheme 415

1. The cut-off valve shall remain activated.
2. Detach the line from the EVAP canister purge valve at the intake manifold.
3. Raise the pressure again, following the instructions in the Kent-Moore manual.
4. Use ultrasonic leak detector J41416 to trace the leak. Start with the line that has been disconnected from the intake manifold and then follow the system lines and components. Make a visual check of the system at the same time. NOTE: In order to check for leaks in components on the top of the fuel tank, it may be necessary to lower the tank a bit. NOTE: Leak detection listening equipment is sensitive to ambient noise, such as exhaust outlet, air-driven machines, use of blower nozzles, leaking pressurized air connections, etc. Airflow from the ventilation equipment in the workshop can also affect the equipment. All of the items mentioned can cause a similar, but incorrect indication/detection of a leak in the EVAP system.
5. Therefore, always adjust the sensitivity of the ultrasonic leak detector, so that the ambient noise, which often causes interference, is filtered out. NOTE: A larger leak, such as a faulty cut-off valve or a loose line, is difficult to detect as it does not give off the "right noise" to be detected by the ultrasonic leak detector. For this reason, it is essential that you make a thorough visual inspection of the system components, to check for leaks not detected by the equipment.
6. Rectify any leaks detected and test the system again.
7. Restore the car to its normal condition.

Scheme 416

1. Remove the fuel tank. See «FUEL TANK, TO REMOVE»(ref-275848-S21347832282007122900000) .
2. Disconnect the quick-release couplings from the EVAP emission canister and the purge filter.
3. Remove the bolt securing the EVAP emission canister to the bracket.
4. Remove the EVAP emission canister from the tank.

Scheme 417

1. Fit the EVAP emission canister to the tank.
2. Fit the bolt securing the EVAP emission canister to the bracket.
3. Connect the quick-release couplings to the EVAP emission canister and the purge filter.
4. Fit the fuel tank. See «FUEL TANK, TO FIT»(ref-275848-S11166789162007122900000) .

Scheme 418

1. Remove the fuel tank. See «FUEL TANK, TO REMOVE»(ref-275848-S21347832282007122900000) .
2. Unplug the connector and remove the pressure sensor.

Scheme 419

1. Fit the pressure sensor and plug in the connector.
2. Fit the fuel tank. See «FUEL TANK, TO FIT»(ref-275848-S11166789162007122900000) .

Scheme 420

1. Remove the fuel tank. See «FUEL TANK, TO REMOVE»(ref-275848-S21347832282007122900000) .
2. Unplug the connector and disconnect the quick-release coupling from the shut-off valve.
3. Undo the catch and remove the shut-off valve.

Scheme 421

1. Fit the shut-off valve.
2. Plug in the connector and connect the quick-release coupling to the shut-off valve.
3. Fit the fuel tank. See «FUEL TANK, TO FIT»(ref-275848-S11166789162007122900000) .

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Scheme 423

1. Remove the upper engine cover.
2. Remove the connector.
3. Press the lock and hose fast coupling from the valve (exhaust hose to turbo inlet and intake manifold).
4. Carefully bend out the console catch and remove the valve from the console.
5. Press the lock in, release the inlet hose fast coupling, and remove the valve.

Scheme 424

Scheme 425

1. Fit the valve to the console and fold back the catch which retains the valve.
2. Connect the hoses to the valve, check that the fast couplings are locked.
3. Attach the connector.
4. Replace the upper engine cover.

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Brief description

Certain markets have legal requirements governing emissions that are released into the air when refuelling (emission legislation varies on different markets). Hydrocarbons that evaporate in conjunction with refuelling must be handled by the car and not released in to the air. Cars on certain regulated markets are equipped with a system called ORVR (Onboard Refuelling Vapor Recovery), which takes care of the fuel vapor that is released while refuelling. The fuel vapor is collected in an evaporative emission canister through which air passes while the car is being driven to transport the petrol vapor back to the intake system for igniting in the engine.

It is important to ensure the integrity of the tank and its components to prevent emissions into the air. The evaporative emission system has therefore been designed to detect any leaks. A leak corresponding to a hole larger than 0.5 mm (0.020") in diameter must be detected by the evaporative emission system.

System description

Fuel is filled through the fuel filler pipe and passes through the check valve down to the tank. The fuel filler pipe acts as an ejector. Fuel flowing down into the tank is accompanied by air from outside and prevents fuel vapor from being emitted to the surroundings via the opening in the fuel filler pipe. The fuel being filled forces the gaseous hydrocarbons and the air being drawn down into the tank through the float valve into the EVAP emission canister. The hydrocarbons are absorbed in the emission canister and the air is let out through the shut-off valve.

At a certain fuel level, the float valve will close and increase the pressure in the tank. The fuel will now rise in the filler pipe and turn off the flow of fuel when it reaches the nozzle. The check valve in the filler pipe prevents fuel from being ejected from the mouth of the filler pipe when the nozzle closes.

The pressure remaining in the tank is led through the float valve into the evaporative emission canister. As the pressure in the tank is gradually reduced, fuel will run from the filler pipe until it is empty.

When the engine starts, the evaporative emission canister is gradually purged by air being drawn into it via the shut-off valve. Hydrocarbon/air mixture passes through the EVAP canister purge valve into the engine and is ignited.

Scheme 428

The tank has a volume of 62 liters (EU tank: 58 liters). All components on the tank are welded, except for the pressure sensor, fuel pump and EVAP canister.

Scheme 429

Shut-off valve, roll-over, is only closed on roll-over and thus prevents fuel leak.

A line connects the valve to the evaporative emission canister. Vapors which expand in the tank are vented through the valve and canister.

Scheme 430

Roll-over valves are only closed in the event of the car rolling over. This prevents fuel leaks.

A line from each roll-over valve connects the three valves with the fluid trap. The purpose of the fluid trap is to prevent fluid fuel from entering the EVAP canister. A line connects the valve to the EVAP canister. Vapors which expand in the tank are vented through the valves and canister.

Scheme 431

A line connects the float valve to the evaporative emission canister. The float valve prevents fuel in liquid form reaching the canister. During filling up, vapors in the tank are pressed through the float valve into the evaporative emission canister.

A spring-loaded float closes the valve when the tank is full or on roll-over.

Scheme 432

The evaporative emission canister is placed on the right-hand side of the tank and consists of a container filled with a special pelletized charcoal. Pelletized charcoal is used to give as little back pressure as possible from the canister. Hydrocarbons which have vaporized in the tank are passed through a line to the canister. During filling up, the hydrocarbons and air from the tank are evacuated via a line to the carbon filter which absorbs the hydrocarbons.

Lines connect the evaporative emission canister with the fuel tank, purge valve and shut-off valve. When the engine starts, air is drawn through the shut-off valve to the canister and then via the purge valve into the intake manifold. The hydrocarbons follow and are burned in the engine.

The evaporative emission canister absorbs around 70 g hydrocarbon per tank filling. During driving, the canister is purged; the time required for this depends on the driving style. The canister can absorb a maximum of around 125 g hydrocarbons.

Scheme 433

The evaporative emission canister is placed on the right-hand side of the tank and consists of a container filled with a special pelletized charcoal. Pelletized charcoal is used to give as little back pressure as possible from the canister. Hydrocarbons which have vaporized in the tank are passed through a line to the canister.

During filling up, the hydrocarbons and air from the tank are evacuated via a line to the carbon filter which absorbs the hydrocarbons.

Lines connect the EVAP canister with the fuel tank and purge valve. When the engine starts, air is drawn through the shut-off valve to the canister and then via the purge valve into the intake manifold. The hydrocarbons follow and are burned in the engine.

Scheme 434

The check valve is normally closed and only allows flow in the direction to the tank.

In this way the valve prevents "back-spit" on nozzle shut-off.

Scheme 435

Fuel is added through the filler pipe and then based through a check valve into the tank.

At the top of the filler pipe is an insert that provides a good fit around the fuel pump nozzle when refuelling. The insert also includes an ejector. (EU tank does not have an ejector.)

Scheme 436

The filler cap is an important part of the tank leakage diagnosis. If the diagnosis shows a leak, Trionic will set a diagnostic trouble code.

Scheme 437

The tank leak diagnosis is used to check that there are no leaks in the evaporative emission system. A leak is characterized by the absence of reduced pressure in the system during diagnosis.

Diagnosis is performed once per trip and the aim is to establish any leak greater than a hole corresponding to 0.5 mm (0.020") in diameter occurring in the evaporative emission system.