Grand Cherokee
- Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. Fuel filter/pressure regulator is located in front of fuel tank, above rear axle. See Figure.
- Install Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel pressure line and fuel filter/pressure regulator. Lower vehicle. Disconnect fuel supply line from fuel rail. Install a second fuel line pressure test adapter hose between disconnected fuel line and fuel rail. Connect 0-60 psi (0-4.2 kg/cm2 ) fuel pressure test gauge from Gauge Set (5069) to test port on appropriate adapter hose.
- Ensure no fuel leaks exist and start engine. Warm engine to normal operating temperature. Fuel pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm2 ). Turn ignition off. Pressure should not fall to less than 30 psi (2.1 kg/cm2 ) for 5 minutes.
- If pressure falls to less than 30 psi (2.1 kg/cm2 ), start engine and warm to normal operating temperature. Turn ignition off. Clamp rubber hose between fuel rail and test port on adapter hose. If pressure still does not hold, repair leaking fuel injector or fuel rail. If pressure holds at 30 psi (2.1 kg/cm2 ) or more, go to next step.
- Remove clamp from hose. Start engine and allow to reach operating temperature. Turn ignition off. Again clamp rubber hose between fuel rail and test port on adapter hose. Raise and support vehicle. Clamp hose between fuel pressure line and fuel filter/pressure regulator. If pressure does not drop to less than 30 psi (2.1 kg/cm2 ) for 5 minutes, check for leaking fuel lines, fuel filter/pressure regulator or connections. Repair fuel system as necessary. If fuel lines, fuel filter/pressure regulator and connections are okay, check valve in fuel pump is defective. Replace fuel pump module.