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.

Fig. 38 Testing the purge control valve:

PURGE CONTROL VALVE

1. Remove the purge control valve.
2. Connect a hand vacuum pump to the vacuum nipple of the purge control valve, Fig. 38.
3. Blow into the canister side nipple and verify that when more than 1.4 in. Hg of vacuum is applied to the purge control valve air flows through the PCV.

Fig. 39 Testing the thermo valve:

THERMO VALVE

1. Disconnect the vacuum hose connected to nipple (A) from the thermo valve and connect a hand vacuum pump to the nipple, Fig. 39.
2. Apply vacuum to the thermo valve and verify that when coolant temperature is less than 16 +/- 3 degrees C (61 +/- 5 degrees F) vacuum leaks through the thermo valve and when coolant temperature is greater than 18 +/- 2 degrees C (64 +/- 4 degrees F) vacuum holds.
3. Disconnect all vacuum hoses from the thermo valve.
4. Connect a hand vacuum pump to nipple (B) or (C) or (D), plug remaining nipples, apply vacuum and verify that when coolant temperature is less than 63 +/- 3 degrees C (145 +/- 5 degrees F) vacuum leaks and when coolant temperature is greater than 65 +/- 2 degrees C (149 +/- 4 degrees F) vacuum holds.

Note: The thermo valve also controls the choke breaker, EGR, and choke opener. If the thermo valve fails and must be replaced use 3M locking sealant 4171 or equivalent and torque the thermo valve to 20 to 40 Nm (15-30 ft. lbs.). Do not use wrenches or pliers on the resin part of the valve during installation.