4. Checking the Vacuum Downstream of the Canister Purge (CP) Valve

ECM-4047 CANISTER PURGE (CP) VALVE/CANISTER SHUT OFF VALVE
LEAK DIAGNOSTIC

Checking the vacuum downstream of the canister purge (CP) valve



Note! As the illustrations in this service information are used for different model years and/or models, some variation may occur. However, the essential information is always correct. Some of the illustrations only apply to C70/S70/V70. However they are also a guide for working on the S80.

- Start the engine and let it idle.
- Disconnect the hose between the canister purge (CP) valve and the EVAP canister from the canister purge (CP) valve.
- Read the canister purge (CP) valve. This is to check whether the valve is activated.

Check that there is a vacuum in the canister purge (CP) valve when the valve is activated.

Is there a vacuum?
Yes - Continue below.
No - Skip to "Checking the Canister Purge (CP) Valve Vacuum"


Checking the vacuum at the EVAP canister



- Ignition off.
- Reconnect the hose on the canister purge (CP) valve.
- Disconnect the hose to the canister purge (CP) valve from the EVAP canister.
- Start the engine and let it idle.
- Read the canister purge (CP) valve value. This is to determine whether the valve is activated or not.

Check that there is a vacuum in the hose when the canister purge (CP) valve is activated.

Is there a vacuum?
Yes - Continue below.
No - Skip to "Checking the Hose"


Checking the EVAP canister
Check that all EVAP canister inlets and outlets are not sealed.

Hint: Connect a vacuum pump to the EVAP canister terminals, one at a time. Check that negative pressure cannot be pumped.

Other information:
- To access/replace the EVAP canister, Carbon Filter Container, Replacing

Was a fault detected?
Yes - Skip to "Verification information"
No - Continue below.


Checking the hose between the fuel tank and the EVAP canister
Check that the hose between the fuel tank and EVAP canister is airtight and is not trapped.

Remedy as necessary.

Was a fault detected?
Yes - Skip to "Verification information"
No - Continue below.


Test pressurization of the fuel tank system



- Max 50 liters of fuel in the fuel tank.
- Ignition off.
- Connect the hose from the fuel tank to the EVAP canister.
- Clamp the hose between the EVAP canister shut-off valve and the EVAP canister with a hose clip to seal it.
- Carefully disconnect the EVAP canister hose from the canister purge (CP) valve.
Connect manometer 999 5646 to the hose and the pressure regulator 999 5544 to the manometer.
Set the pressure to 7 kPa (Read on manometer 999 5646).
The cock must be at right angles to the hoses.

WARNING! Max 10 kpa.

Let the pressure build up for 5 minutes.
Shut off the cock (the pressure may drop 1 - 2 kPa before stabilizing). Read the pressure.
Turn the cock towards the EVAP canister hose.
Wait for 10 minutes.

WARNING! Never leave the car unattended with its fuel tank system pressurized.

The pressure must be stable (it may rise a little due to fuel evaporation).

Is the pressure stable?
Yes - Continue below.
No - Skip to "Checking the Fuel Tank System"


Checking the fuel tank pressure sensor



- Disconnect tool 999 5646.
- Connect the EVAP canister hose.
- Remove the hose clamp from the hose between the canister purge (CP) valve and the intake manifold.
- Start the engine and let it idle.
- Read the value for the fuel tank pressure and the canister purge (CP) valve.

When the canister purge (CP) valve opens, the pressure in the fuel tank must drop.

Is the pressure in the fuel tank dropping?
Yes - Continue below.
No - Skip to "Checking the Fuel Tank Pressure Sensor Hose"


Checking the hose to the EVAP canister shut-off valve
Check the hose to the EVAP canister shut-off valve. Check the seal. Check the terminals.

Remedy as necessary.

Was a fault detected?
Yes - Skip to "Verification information"
No - Continue below.


Replacing the component



Try a new EVAP canister shut-off valve (C70/S70/V70) according to EVAP Canister Shut-Off Valve, Replacing

Skip to "Verification information"


Checking the Fuel Tank Pressure Sensor Hose



- Ignition off.
- Remove the fuel tank pressure sensor.
- Remove the hose with the Y-nipple.

Check that the nipple and hoses are not blocked.

Remedy as necessary.

Was a fault detected?
Yes - Skip to "Verification information"
No - Continue below.


Replacing the component



Try a new fuel tank pressure sensor (C70/S70/V70) according to Fuel Tank Pressure Sensor, Replacing

Skip to "Verification information"


Checking the fuel tank system



- Ignition off.
- Carefully pressurize the fuel tank system to 7 kpa. The cock must be at right angles to the hoses.

Note! Max 10 kpa.

Check the fuel tank system: Spray soapy water from the EVAP canister to the canister purge (CP) valve. Also spray the line between the fuel tank and the EVAP canister shutoff valve. Also check the filler pipe and the fuel tank filler cap.
It may be necessary to lower the fuel tank in order to fault-trace hoses and connectors on top of the fuel tank.

Remedy the leakage.

Skip to "Verification information"


Checking the Hose
Check if the hose between the canister purge (CP) valve and the EVAP canister is blocked or trapped.

Skip to "Verification information"


Checking the Canister Purge (CP) Valve Vacuum



- Connect the hose between the canister purge (CP) valve and the EVAP canister to the canister purge (CP) valve.
- Start the engine and let it idle.
- Disconnect the hose between the canister purge (CP) valve and the intake manifold from the canister purge (CP) valve.

Check that there is a vacuum in the hose.

Remedy as necessary.

Was a fault detected?
Yes - Skip to "Verification information"
No - Continue below.


Replacing the component



Try a new canister purge (CP) valve according to Canister Purge (CP) Valve, Replacing


Verification information
Hint: After carrying out the check and the repair, check that the fault has been remedied.

Continue with "Starting the Quick Test" 2. Starting the Quick Test