Acura NSX 1991 Manual page 281

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Evaporative Emission (EVAP) Two Way Valve Testing
1. Remove the fuel fill cap.
2. Remove vapor line from the fuel tank and connect
to T-fitting from vacuum gauge and vacuum pump
as shown.
VACUUM/PRESSURE GAUGE
0-4 in. Hg
07JAZ-001000 A
VACUUM PUMP/
GAUGE
A973X-041-XXXXX
T-FITTING
3. Apply vacuum slowly and continuously while watch-
ing the gauge.
Vacuum should stabilize momentarily at 0.7 - 2.0 kPa
(5 - 15 mmHg, 0.2 - 0.6 in.Hg).
• If vacuum stabilizes (valve opens) below 0.7 kPa
(5 mmHg, 0.2 in.Hg) or above 2.0 kPa (15 mmHg,
0.6 in.Hg), install new valve and retest.
4. Move vacuum pump hose from vacuum to pressure
fitting, and move vacuum gauge hose from vacuum
to pressure side as shown.
Table of Contents
PRESSURE SIDE
5. Slowly pressurize the vapor line while watching the
gauge.
Pressure should stabilize at 1.3 - 4.7 kPa (10 - 35
mmHg, 0.4- 1.4 in.Hg).
• If pressure momentarily stabilizes (valve opens)
at 1.3 - 4.7 kPa (10 - 35 mmHg, 0.4 - 1.4 in.Hg),
the valve is OK.
• If pressure stabilizes below 1.3 kPa (10 mmHg,
0.4 in.Hg) or above 4.7 kPa (35 mmHg, 1.4 in.Hg),
install a new valve and retest.