Checking blockage between tank pressure sensor and tank
HINT: If a small leak is detected after a quick test of the tank system, in may be due to blockage between the tank pressure sensor and the tank.
HINT: The method below is used to determine if the small leak detected after the quick test is caused by blockage between the tank pressure sensor and tank. This is done by running the test with the tank cap removed. Normally, a major leak is detected if the cap is off. If a small leak is detected when the tank cap is off, there is a blockage between the tank pressure sensor and the tank.
HINT:
If the canister is filled with fuel vapor, the test is interrupted. The canister fills with fuel vapor more quickly if the canister purge valve is regulating and the tank cap is removed. Therefore, start the quick test immediately after engine start and do not allow the engine to idle more than necessary.
- Remove the tank cap.
- Engine idling
- Start the quick test with the tank cap removed.
Especially check tank pressure (yellow line) during the test for major leaks.
If a major leak is detected when the tank cap is off, the cause of the fault is likely leakage. Continue fault tracing as described for a small leak.
If the test is interrupted or a small leak is detected when the tank cap is removed and tank pressure (yellow line) drops more quickly than normal during the test, there may be blockage in a hose or hose connection between the tank and tank pressure sensor. This can be fault traced by detaching the hoses to EVAP system components (one at a time) and performing a quick test for each. If a major leak is detected after the quick test when the hose has been disconnected, the fault is against the direction of airflow (calculated from the disconnected hose).
HINT: Airflow direction during the quick test can be calculated from the fuel tank: fuel tank, canister, canister purge valve, intake pipe. The tank pressure sensor measures the pressure in the hose between the fuel tank and the canister.
HINT: If, for example, the hose to the canister is detached from the fuel tank and a major leak is detected, there is a blockage in the tank hose connection.
Remedy as necessary.
Restore all components and then perform a quick test of the tank system before delivering the vehicle to the customer.
Select an alternative to continue:
- Continue fault tracing for small leak.
Refer to Small leak
- Exit.
OKAY: Troubleshooting has been completed.
- Continue fault tracing for small leak.