Description
The check valve maintains constant pressure at the fuel injectors. When the pressure difference between the fuel and intake manifolds exceeds 250 kPa (2.55 kg/cm2) (engines D16Y4, D16Y9 - 294 kPa, 3.0 kg/cm2), the diaphragm is pushed up and excess fuel is drained into the tank through the return line.
Closed state:
Open state:
Examination
Caution: Do not smoke during the test. Keep open flames away from the workplace.
1. Attach a special tool to the service hole of the fuel line (on the filter).
The pressure should be:
- Engines D14A3, D14A4, D15Z4, D15Z5: 226-275 kPa (2.3-2.8 kg/cm2)
- Engines D16Y4, D16Y9: 275-324 kPa (2.7-3.2 kg/cm2)
(With the return valve vacuum hose disconnected and clamped)
2. Connect the vacuum hose to the return valve.
3. Verify that fuel pressure increases when the vacuum hose is disconnected from the check valve again.
If fuel pressure does not increase, replace the check valve.
Replacement
Warning: Do not smoke while working on the fuel system. Keep open flames away from the workplace.
1. Place a cloth under the return valve, then release the fuel pressure.
2. Disconnect the vacuum hose and fuel return hose.
3. Unscrew the 2 M6 mounting bolts.
Note. Replace the O-ring. When installing the check valve, lubricate the O-ring with engine oil and place it in the correct place, being careful not to damage the O-ring.