B4000 4WD V6-4.0L OHV (1995)
2. Disconnect the vacuum hose from the pressure regulator and plug it.
3. Start the engine and drive the vehicle under heavy acceleration.
4. Verify that the fuel line pressure does not increase or decrease more than 20 kPa (O.2 kg/cm2, 3 psi) during heavy acceleration.
5. If not as specified, perform the following inspection:
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Fuel vapor valve
6. If the fuel vapor valve is ok, replace the fuel filter.