Chart A-7, Fuel System Pressure Test, GSI: Notes

Fuel pump delivers fuel to fuel rail and fuel injectors with fuel pressure maintained at 38-44 psi (2.7-3.1 kg/cm² ) by pressure regulator. Excess fuel is returned to fuel tank. With engine stopped, fuel pump can be energized by applying battery voltage to check connector located in engine compartment, on left strut tower. With engine off, fuel pressure should remain greater than 21 psi (1.5 kg/cm² ) for 5 minutes. ECM controls fuel pressure Vacuum Switching Valve (VSV), which supplies vacuum to pressure regulator. Fuel pressure VSV is mounted on end of intake manifold.

1. Release fuel pressure before disconnecting fuel lines. Wrap fuel line with shop towel before disconnecting fuel lines.
2. With engine idling, high manifold vacuum is applied to pressure regulator, resulting in a lower fuel pressure of 30-33 psi (2.1-2.3 kg/cm² ).
3. Applying vacuum to pressure regulator should decrease fuel pressure.
4. If fuel pressure decreases quickly, it may be caused by one of the following: defective fuel pump check valve, fuel lines leaking, leaking pressure regulator or fuel injectors stuck open.
5. Fuel pressure less than 38 psi (2.7 kg/cm² ) may be caused by defective pressure regulator or restricted fuel flow. Low fuel pressure may result in hard starting and poor driveability, and Code 25 may be set.
6. Restricting fuel return line allows fuel pump to obtain maximum fuel pressure. With battery voltage applied to FP terminal, fuel pressure should be greater than 65 psi (4.6 kg/cm² ).
7. This determines if high fuel pressure is caused by a restricted fuel return line or defective pressure regulator.