Major Leak - Permanent Fault

ECM-4308 LEAK DIAGNOSTIC LARGE LEAK
MAJOR LEAK - PERMANENT FAULT

Safety
First read Service Precautions


Checking hoses and pipes
Check that the fuel tank filler cap is on properly and that its seal is intact.
Check that the hoses and hose connectors at the EVAP canister, EVAP canister shut-off valve and fuel tank are not leaking or pinched.

Remedy as necessary.

Carry out a quick test of the fuel system.


General about fuel tank system test



The engine management system has a built-in function for carrying out a quick check of fuel tank system sealing. By activating the function, the control module is able to determine whether the fuel tank system is fault free or if there is any leakage faster than usual. The condition for the test is that no diagnostic trouble codes (DTCs) are stored, engine temperature is above 70°C (158°F) and that the engine is idling.

For further information about fuel tank system test diagnostics, Leak Diagnostics

- Canister purge (CP) valve
- EVAP canister
- EVAP canister shut-off valve
- Fuel tank pressure sensor
- Air cleaner (ACL)


Checking the engine coolant temperature (ECT)



Note: If the engine coolant temperature (ECT) is under 70°C (158°F) the test cannot start.

- Start the engine.
- Read off engine coolant temperature (ECT)
If the engine coolant temperature (ECT) is under 70°C (158°F) allow the engine to reach operating temperature or interrupt the test.

Is the temperature above 70°C (158°F)?
Yes - Continue below.
No - Abort test.


Start the fuel tank system test

Note: If the engine coolant temperature (ECT) is under 70°C (158°F) the test cannot start.

- Engine idling.
- Start the quick test

Leak diagnostic active
This parameter displays that test is underway. When the parameter displays YES and has returned to NO the test is ready or has been interrupted.

Fault status
These parameters display the status of those diagnostic tests which are included in the leak diagnostic.

The following alternatives are available:
1 When the active leak diagnostic has displayed YES and then NO and all fault status have moved to clear, fault not found, the test has been run without any faults being found.
2 When the active leak diagnostic has displayed YES and then NO and one of the fault status displays fault found. A fault has been detected in that part of the test.
3 When the active leak diagnostic has displayed YES and then NO and one or several of the fault statuses has not gone and no fault is detected. Or if active leak diagnostic unchanged status to YES. The test has not started or been interrupted. Try again or select 3 to interrupt.

Select an alternative
1 - Testing Complete.
2 - Continue below.
3 - Testing Complete.


Testing vacuum downstream of the canister purge (CP) valve



- Start the engine and let it idle.
- Disconnect the hose between the canister purge (CP) valve. This is to check whether the valve is activated.
Check that htere is vacuum in the canister purge (CP) valve when the valve is activated.

Is there vacuum?
Yes - Continue below.
No - Skip to "Checking vacuum to canister purge (CP) valve"


Checking the vacuum at the EVAP canister



- Ignition off.
- Reinstall 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 - Checking hose
Check if the hose between the canister purge (CP) valve and EVAP canister is blocked or trapped.
Skip to "Verifiaction


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.

Was a fault detected?
Yes - Skip to "Verifiaction
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 "Verifiaction
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 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"
No - Try a new EVAP canister shut-off valve according to EVAP Canister Shut-Off Valve, Replacing
Skip to "Verification"


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"
No - Try a new fuel tank pressure sensor according to Fuel Tank Pressure Sensor, Replacing
Skip to "Verification"


Checking vacuum to canister purge (CP) valve



- 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"
No - Continue to "Replacing component"


Replacing component



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


Verification



- Ignition off.
- Reinstall the hoses/components.
- Start the engine.
Activate the quick fuel tank system test.

Does the diagnostic trouble code (DTC) recur?
Yes - Continue below.
No - Testing Complete.


Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed. Exit fault tracing for this diagnostic trouble code (DTC) or make another attempt.