Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Chart A-7, Fuel System Pressure Test
With ignition on, ECM activates fuel pump. Fuel pump operates as long as engine is cranking or running, and ECM is receiving reference pulses. If no reference pulses are received, ECM will turn off fuel pump approximately 2 seconds after reference pulses stop. The ECM is located below left side of instrument panel.
Fuel pump delivers fuel to fuel rail and fuel injectors, then to pressure regulator where system pressure is maintained at approximately 23.2-30.5 psi (1.6-2.1 kg/cm2 ), depending on engine operating conditions. Excess fuel is returned to fuel tank.
- Release fuel pressure before disconnecting fuel lines. Wrap fuel line with shop towel before disconnecting fuel lines. With ignition on, fuel pressure should be approximately 23.2-30.5 psi (1.6-2.1 kg/cm2 ). Fuel pressure is controlled by spring pressure in pressure regulator.
- With engine idling, high manifold vacuum is applied to pressure regulator, resulting in a lower fuel pressure.
- Fuel pressure that decreases quickly 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 injector that is leaking and stuck open can be determined by a fouled or saturated spark plug. Pressurize fuel system and check for leaking fuel injector.
- Fuel pressure less than 23.2 psi (1.6 kg/cm2 ) may cause a lean condition, resulting in hard starting and poor driveability, if engine will start. Restricted flow may allow engine to run at idle or low speeds, but causes a surge and engine stall in acceleration.
- Restricting fuel return line allows fuel pump to develop maximum fuel pressure. When battery voltage is applied to fuel pump test terminal, fuel pressure should be greater than 30.5 psi (2.1 kg/cm2 ).
- This determines if high fuel pressure is caused by a restricted fuel return or defective pressure regulator.
Use the Manual With the Right Hardware
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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.
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