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Fuel System Pressure Test (Grand Cherokee)
- Fuel system on Grand Cherokee is equipped with a mechanical pressure regulator, mounted on fuel pump module, which is not controlled by PCM or engine vacuum. With engine at idle, pressure should be 37-41 psi (2.6-2.9 kg/cm2
).
- Remove protective cap at fuel rail. Connect a 0-60 psi (0-4.2 kg/cm2
) fuel pressure gauge to test port fitting on fuel rail. With engine at idle, pressure should be 37-41 psi (2.6-2.9 kg/cm2
). If pressure is zero, see TESTS W/CODES - 4.0L
article in the ENGINE PERFORMANCE section. If operating pressure is above 41 psi (2.9 kg/cm2
), fuel pump is okay but fuel pressure regulator is defective. Replace fuel pump module assembly.