Evaporative Emissions System: Testing and Inspection

Fig. 115 Testing the bowl vent valve:

BOWL VENT VALVE

CAUTION!

Check the bowl vent valve after the engine has been allowed to cool. If the engine is hot fuel can gush out of the BVV nipple.

1. Remove the air cleaner.
2. Disconnect the bowl vapor hose from the bowl vent valve (BVV) nipple and connect a hand vacuum pump to the BVV nipple, Fig. 115.
3. Apply a vacuum of 20 kPa (6.0 in. Hg) to the BVV and verify that when the engine is running at idle the BVV holds vacuum and leaks when the engine is stopped.

Overfill Limiter (Two Way Valve):

OVERFILL LIMITER VALVE

Remove the overfill limiter valve and blow gently through both ends. Air should pass through the valve in both directions with slight resistance.


PURGE CONTROL VALVE

1. With the engine warmed up to normal operating temperature and ignition key in the "OFF" position, remove the purge hose from the air cleaner and blow into it. Air should not flow through the purge control valve.
2. Start the engine and accelerate it to 2000 rpm. Blow into the hose and verify that air passes through the purge control valve.
3. If air will not pass check the operation of the thermo valve and its connecting vacuum hoses for breaks and obstructions.