| 1. Check a condition of hoses and connections. |
| 2. Disconnect a vacuum hose from the coal filter and connect a vacuum manometer. When the engine is not heated-up and idles, depression should be absent. If depression is present, probably, the blowing-off valve is faulty. Warm up the engine and check depression existence. If is not present, replace the blowing-off valve. |
| 3. Check, that the bilateral valve located near the coal filter did not pass air. |
| 4. Check tension giving on the blowing-off valve. |
| 5. Check the coal filter on leak existence. |