Fuel pump delivers fuel to fuel rail and fuel injectors with fuel pressure maintained at 35-38 psi (2.5-2.7 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.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Release fuel pressure before disconnecting fuel lines. Wrap fuel line with shop towel before disconnecting fuel lines.
With engine idling, high manifold vacuum is applied to pressure regulator, resulting in a lower fuel pressure of 30-35 psi (2.2-2.5 kg/cm² ).
Applying vacuum to pressure regulator should decrease fuel pressure.
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.
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.
Restricting fuel return line allows fuel pump to obtain maximum fuel pressure. When battery voltage is applied to FP terminal, fuel pressure should be greater than 65 psi (4.6 kg/cm² ).
This tests determines if high fuel pressure is caused by a fuel line restriction or defective pressure regulator.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

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

Use the Manual With the Right Hardware

When to See a Mechanic

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