EVAP Two Way Valve Test

Remove the fuel fill cap.
Disconnect the vapor line from the EVAP two way valve (A). Connect it to a T-Fitting from the vacuum gauge and the commercially available vacuum pump/gauge, 0-30 in. Hg (A973X-041-XXXXX or Snap-On YA4000A or equivalent)

Fig 1: Disconnecting The Vapor Line From The EVAP Two Way Valve
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Apply vacuum slowly and continuously while watching the gauge. The vacuum should stabilize momentarily at 0.8-2.1 kPa (6-16 mmHg, 0.2-0.6 in.Hg).
If the vacuum stabilizes (valve opens) below 0.8 kPa (6 mmHg, 0.2 in.Hg) or above 2.1 kPa (16 mmHg, 0.6 in.Hg), install a new valve and retest.
Move the vacuum pump hose from the vacuum fitting to the pressure fitting, and move the vacuum gauge hose from the vacuum side to the pressure side (A) as shown.

Fig 2: Moving The Vacuum Pump Hose From The Vacuum Fitting To The Pressure Fitting, And Moving The Vacuum Gauge Hose From The Vacuum Side To The Pressure Side
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Slowly pressurize the vapor line while watching the gauge. The pressure should stabilize momentarily above 1.0 kPa (8 mmHg, 0.3 in.Hg).
- If the pressure momentarily stabilizes (valve opens) above 1.0 kPa (8 mmHg, 0.3 in.Hg), the valve is OK.
- If the pressure stabilizes below 1.0 kPa (8 mmHg, 0.3 in.Hg), install a new valve and retest.