Evaporative Controls System Diagnostic Test Procedure

Evaporative Control System:

EVAP SYSTEM DIAGRAMS


TWO-WAY VALVE TEST:
1. Remove the fuel filler cap.
2. Remove vapor line from the fuel tank and connect a vacuum/pressure gauge and pump via a T-fitting.

Two Way Valve Testing:

3. Apply vacuum slowly while watching the gauge.
Vacuum should stabilize momentarily at 0.2 to 0.6 in.Hg (5 to 15 mmHg).
If vacuum stabilizes (valve opens) below 0.2 in.Hg (5 mmHg) or above 0.6 in.Hg (15 mmHg), install new valve and retest.
4. Move vacuum pump hose from vacuum to pressure side.

Two Way Valve Testing:

5. Slowly pressurize the vapor line while watching the gauge.
Pressure should momentarily stabilize at 0.4 to 1.4 in.Hg (10 to 35 mmHg).
If pressure stabilizes (valve opens) below 0.4 in.Hg (10 mmHg) or above 1.4 in.Hg (35 mmHg), install new valve and retest.