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
- there is too much fuel in the tank
- high fuel vaporization
- a blockage between the fuel tank pressure sensor and the fuel tank.
HINT: 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.
HINT:
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 quick test is not cancelled when the fuel tank filler cap is 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 quick test is cancelled or "small leak" is detected when the fuel tank filler cap is 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.
HINT: 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.
Select a suitable alternative to continue:
- Continue the fault-tracing for the diagnostic trouble code (DTC)
- Finish.
OKAY: Troubleshooting has been completed.