Acura NSX 1997 Service Manual page 276

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Emission Control System
Evaporative Emission (EVAP) Two Way Valve Testing
1. Remove the fuel fill cap.
2. Remove the vapor line from the EVAP two way
valve (located under the engine compartment
fuse/relay box), and connect it to a T-fitting from a
vacuum gauge and a vacuum pump as shown.
VACUUM/PRESSURE
GAUGE,
0-4in.Hg
07JAZ-001000B
VACUUM PUMP/
GAUGE
A973X - 041 -
XXXXX
T-FITTING
3. 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.
4. Move the vacuum pump hose from the vacuum fit-
ting to the pressure fitting, and move the vacuum
gauge hose from the vacuum side to the pressure
side as shown.
PRESSURE
SIDE
5. Slowly pressurize the vapor line while watching the
gauge. The pressure should be 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.
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