Quick Test of the Fuel Tank System
Quick test of the fuel tank system
General information about testing the fuel tank system
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 determines faster than usual whether the fuel tank system is fault free or if there is any leakage. The conditions for this test are that:
- Engine idling
- The engine coolant temperature (ECT) is higher than 70 °C
- There is not too much fuel in the tank
- Fuel evaporation is not too high during the leakage test (increased evaporation gives a pressure increase in the tank system).
The amount of vaporization permitted varies depending on the leakage test. Higher vaporization is permitted for the 1.0 mm than the 0.5 mm leakage test. If the test for 1.0 mm leaks starts but not for 0.5 mm leaks ("Smallest leak"), it may be because the fuel vaporization is too high.
Hint: There is high vaporization in warm conditions. Vaporization increases also if winter fuel is used in warm conditions. Fuel vaporization can be decreased by allowing the fuel to cool. If there is difficulty spray water on the fuel tank to speed up the fuel cooling down.
For further information about the fuel tank system diagnostic, see Leak diagnostic Leak Diagnostic.
1. Canister purge (CP) valve
2. EVAP canister
3. EVAP canister shut-off valve
4. Fuel tank pressure sensor
5. Air cleaner (ACL).
Location Of Components:
Continue - check
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Diagnostic trouble codes (DTCs), check
Note! The test cannot be started if diagnostic trouble codes (DTCs) are stored. Therefore it is important to check if any diagnostic trouble codes (DTCs) are stored.
- Ignition on
- Read off diagnostic trouble codes (DTCs).
If diagnostic trouble codes (DTCs) are stored, the test must be interrupted. Fault-trace the diagnostic trouble codes (DTCs) first.
Are any diagnostic trouble codes (DTCs) stored?
Yes - DONE
No - check
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Engine coolant temperature (ECT), check
Note! The test cannot be started if the engine coolant temperature (ECT) is below 70°C.
- Start the engine
- Read off the engine coolant temperature (ECT) sensor.
If the engine coolant temperature is below 70°C, wait until the engine has reached operating temperature.
Continue
Continue - starting the quick test
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Fuel tank system, starting the quick test
Note! The test cannot be started if the engine coolant temperature (ECT) is below 70 °C.
- Engine idling
- Start the quick test.
Swift test running status
This parameter indicates that the test is running.
- RUNNING
- NOT RUNNING.
Fault status
These parameters display the status of those diagnostic tests which are included in the leak diagnostic.
- Status failure canister close valve
- Status failure rough leak
- Status failure PCV open
- Status failure small leak
- Status failure smallest leak.
The test is run in the designated order.
The parameters can assume three values depending on the test result.
- NOT READY
- READY NO FAULT
- READY FAULT FOUND.
Other parameters
- Fuel tank pressure (red line)
- EVAP canister shut-off valve closes at activation, ON (green line)
- Canister purge (CP) valve (yellow line).
Swift test, sequence
The entire Swift test is run twice. The difference between the two tests is that the "Small leak" parameter is run during the first test, while the "Smallest leak" parameter is run during the second test.
Swift test starts with"Start reading"
The quick test starts and "RUNNING" is displayed in the status window. The test runs in the above order (see fault status).
The test can be stopped in three different ways, "NOT RUNNING".
- The quick test is finished
- The quick test has detected a fault
- Physical faults in the car may be the result of the integrated values reaching their limits because the evaporative emission system (EVAP) canister is too full for example.
The test is cancelled when the first test is complete and no faults are registered. "READY NO FAULT FOUND" is displayed in the four test boxes on the left hand side. The prevailing idling conditions must be made invalid and the original idle speed conditions re-established before the second test can be started. This is done by pressing and then releasing the accelerator pedal (AP). The test restarts and all diagnostic tests are run again up to and including the "Smallest leak" parameter.
The test is complete when "READY NO FAULT FOUND" is displayed in all fault status windows at the same time that "NOT RUNNING" is displayed in the status window.
If the test detects a fault, "READY FAULT FOUND", the fault must be remedied before the test can be fully run.
If the test is stopped, "NOT RUNNING" is displayed in the status window and "NOT READY" is displayed in the test window, the test must be restarted. This is done by switching off the engine and then switching it on again while starting the swift test at the same time.
Select an option below:
1. Finish
2. Check fault causes in the event of problems running the quick test or "small leak" being detected.
1 - DONE
2 - Checking the cause of a fault using quick test
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Checking the cause of a fault using quick test
Hint: If the quick test does not start or is cancelled before it is complete it may be because:
- The engine coolant temperature (ECT) is lower than 70 °C
- Too much fuel in the fuel tank
- High fuel vaporization
- Blockage between the fuel tank pressure sensor and the fuel tank.
The method below is used to determine whether the cause of the problem is high vaporization or a blockage between the fuel tank pressure sensor and the fuel tank. It can be carried out by running the test with the fuel tank filler cap removed. Normally "large leak" is detected with the fuel tank filler cap removed.
Note! If the EVAP canister fills with the fuel vapor the test is interrupted. The EVAP canister fills with fuel vapor faster if the evaporative emission system (EVAP) valve is operating and the fuel tank filler cap is removed. Start the quick test directly after engine start and do not let the engine run at idle speed for longer than necessary.
- Remove the fuel tank filler cap
- Engine idling
- Start the quick test with the fuel tank filler cap removed.
In particular check the fuel tank pressure (red line) when the "large leak" test is running.
If the quick test is not cancelled when the fuel tank filler cap removed and "large leak" is detected after the quick test is complete, the fuel vaporization is too high. Fuel vaporization can be decreased by allowing the fuel to cool. If there is difficulty spray water on the fuel tank to speed up the fuel cooling down.
If the quick test is cancelled or "small leak" is detected when the the fuel tank filler cap removed and the fuel tank pressure (red line) falls more quickly than normal during the test, it may be due to a blockage in the hose or hose terminal between the tank and the fuel tank pressure sensor. This can be fault-traced by removing the hoses to the evaporative emission (EVAP) system components one at a time and carrying out a quick test between each operation. If a "large leak" is detected after the quick test when the hose has been disconnected the fault is in the direction of the airflow (calculated from the hose that has been disconnected).
Hint: The direction of airflow during a quick test can be calculated from the fuel tank: fuel tank, evaporative emission system (EVAP) canister, evaporative emission system (EVAP) valve. The fuel tank pressure sensor measures the pressure in the hose between the fuel tank and the evaporative emission system (EVAP) canister.
If the hose for the EVAP canister is detached from the fuel tank and a "large leak" is detected, there is a blockage in the tank hose terminal.
Remedy as necessary.
Reset all the components. Carry out a quick test of the tank system before the car is delivered to the customer.
Continue - DONE
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