Grand Cherokee
NOTE:
Grand Cherokee is equipped with a mechanical fuel pressure regulator. Fuel filter/pressure regulator is located in front of fuel tank, above rear axle. See Fig 1. Excess fuel is returned to tank through fuel return line and fuel pressure regulator.
- Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Remove test port cap. Install a 0-60 psi (0-4.2 kg/cm2 ) fuel pressure gauge at test port.
- Start engine and allow to idle. Fuel pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm2 ). If no fuel pressure exists, fuel pump relay control circuit may be defective. See DTC P1282: FUEL PUMP RELAY CONTROL CIRCUIT under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - GRAND CHEROKEE article.
- If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, check fuel return line for kinks or restrictions. If fuel return line is okay, replace fuel filter/pressure regulator. If fuel pressure is as specified, fuel system is okay. Diagnose by symptom. See TROUBLE SHOOTING - NO CODES article.
- If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel supply line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. See Fig 1. Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm2 ). If fuel pressure is within specification, stop ASD fuel system activation, release fuel pressure and replace fuel filter/pressure regulator. If fuel pressure is not within specification, stop ASD fuel system activation, release fuel pressure and replace fuel pump module.
WARNING:
High fuel pressure may be present in fuel lines. Open fuel system with caution. See FUEL SYSTEM PRESSURE RELEASE .