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Grand Cherokee

    NOTE: Two 5/16" Fuel Line Pressure Test Adapter Hose Tools (6539) are required for the following test.
    NOTE: The fuel filter/pressure regulator is located in front of the fuel tank and above the rear axle. See Figure . It is transversely mounted to a chassis crossmember (left-to-right). The fuel filter/regulator is equipped with 3 fuel line fittings (2 at one end and 1 at the other end). The single fitting facing the left side of the vehicle is the supply line to the fuel rail. The 2 fittings, facing the right side of the vehicle are connected to the fuel tank. Of these 2 fittings, the fitting towards the front is used for fuel return to the fuel tank. The fitting towards the rear is a pressure line. This rear fitting must be disconnected for the following step.
  1. Relieve fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE  .
  2. Disconnect fuel pressure line at rear of fuel filter/regulator. This is a 5/16" quick-connect fitting. See Figure . Obtain correct Fuel Line Pressure Test Adapter Hose Tool (6539) for 5/16" fuel lines. Connect one end of this Special Tool into the disconnected fuel pressure line. Connect the other end of the Tool into fitting on fuel filter/regulator. Lower vehicle.
  3. Disconnect the fuel inlet line at fuel rail. On some engines, air cleaner housing removal may be necessary before fuel line disconnection. Obtain a second Fuel Line Pressure Test Adapter Hose Tool (6539) for 5/16" fuel lines. Connect this tool between disconnected fuel line and fuel rail. See Figure .
  4. Install a 0-60 psi (0-4.2 kg/cm2 ) fuel pressure gauge at test port on fuel line pressure test adapter hose. Start engine and bring to normal operating temperature. Observe test gauge. Normal operating pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm2 ). Turn ignition off.
  5. Pressure should not fall below 30 psi for 5 minutes. If pressure falls below 30 psi, it must be determined if a fuel injector, the check valve within the fuel pump module, fuel filter/pressure regulator or a fuel tube/line is leaking. Again, start engine and bring to normal operating temperature. Turn ignition off.
  6. This test step checks for fuel injector or fuel rail leakage. Clamp off the rubber hose portion of fuel line pressure test adapter hose between the fuel rail and the test port "T" on fuel line pressure test adapter hose. If pressure now holds at or above 30 psi, a fuel injector or the fuel rail is leaking. Repair as necessary and retest. If pressure still falls below 30 psi, go to next step.
  7. This step checks for fuel filter/pressure regulator leakage. Again, start engine and bring to normal, operating temperature. Turn the ignition off. Raise vehicle. While continuing to securely clamp between the fuel rail and the test port "T" on fuel line pressure test adapter hose, securely clamp off any rubber hose portion of the fuel line pressure test adapter hose that was installed between the fuel pressure line and the fuel filter/regulator fitting (by, restricting the pump module supply line's backflow, you isolate any leakdown originating from the fuel filter/regulator via the tank return line) If the pressure falls below, 30 psi within 5 minutes, the fuel filter/regulator is leaking. If it now holds at or above 30 psi, the electric fuel pump check valve is leaking or a fuel tube/line is leaking. A fuel odor presence would indicate the latter. The electric fuel pump is not serviced separately. If replacement is necessary, replace the fuel pump module assembly. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL & INSTALLATION - GRAND CHEROKEE article. The fuel filter/regulator may be replaced separately.
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