Evaporative Emissions System: Testing and Inspection

Fig 9a:

Evaporative emission control system malfunctions (When tank filler tube cap is removed, pressure releasing noise is heard)
- Incorrect Installation of vapor line -- Correct
- Disconnected vapor line piping joint -- Correct
- Folded, bent, cracked or clogged vapor line -- Replace
- Faulty fuel tank filler tube cap -- Replace


PURGE CONTROL SYSTEM INSPECTION
1. Disconnect the vacuum hose from the throttle body and connect it to a hand vacuum pump, Fig. 9-a.
2. Plug the nipple where the vacuum hose was removed, Fig. 9-a.
3. When the engine is at operating temperature [Engine coolant temperature: 80°C (176°F) or higher], apply vacuum at idle to check the condition of the engine and the vacuum.

Vacuum / Engine status / Normal Condition
53 kPa (15.7 in.Hg.)
Right after starting engine - Vacuum is maintained
10 or more seconds later - Vacuum leaks

Fig 9b:

PURGE PORT VACUUM INSPECTION
1. Disconnect the vacuum hose from the throttle body purge vacuum nipple and connect a hand vacuum pump to the nipple, Fig. 9-b.
2. Start the engine and raise the speed. Vacuum should be kept constant regardless of the increased engine speed.

NOTE: If no vacuum is generated, the throttle body purge port may be clogged.