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HOMESERVICE MANUALSDODGE AND RAM1999DAKOTA SLT, 2D PICKUP, 3.9 X, 4WD, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - BASIC ENGINE TESTING - GASOLINEFUEL SYSTEMFUEL PRESSURE LEAKDOWN TEST
1999 Dodge and Ram Dakota SLT, 2D Pickup, 3.9 X, 4WD, Standard

Fuel Pressure LEAKDOWN Test

1999 Dodge and Ram Dakota SLT, 2D Pickup, 3.9 X, 4WD, StandardSECTION Fuel Pressure LEAKDOWN Test
NOTE: Perform FUEL PRESSURE LEAKDOWN TEST in conjunction with FUEL PUMP CAPACITY TEST and FUEL PUMP PRESSURE TEST. See FUEL PUMP CAPACITY TEST and FUEL PUMP PRESSURE TEST.
  1. Release fuel system pressure. See FUEL PRESSURE RELEASE. Remove air cleaner housing (if necessary) to access quick-connect fuel fittings. Disconnect fuel supply line quick-connect fittings at fuel rail. Connect Fuel Line Pressure Test Adapter (6539 ) for 5/16" fuel lines, or Fuel Line Pressure Test Adapter (6631 ) for 3/8" fuel lines, to the disconnected fuel supply line.
    2. NOTE: Ensure all fittings on tools and lines are in good condition and are not leaking prior to performing this test or fuel pressure readings may be incorrect.
  2. Connect 0-60 psi fuel pressure test gauge to test port on appropriate Fuel Line Pressure Test Adapter. Start engine and bring to normal operating temperature. Observe fuel pressure test gauge. Fuel system pressure should be 44-54 psi (3.1-3.8 kg/cm2 ). Shut engine off. Fuel system pressure should not fall below 30 psi (2.1 kg/cm2 ) for 5 minutes. Go to next step.
  3. If fuel system pressure falls below 30 psi (2.1 kg/cm2 ), check fuel injector, check valve inside fuel pump module or fuel tube/line for leaks. To diagnose components and pinpoint fuel system leaks, perform the following tests:

    1. Fuel Injector Or Fuel Rail Leakage

      Start engine and operate at idle for 2 minutes. Shut off engine. Clamp off rubber hose portion of Fuel Line Pressure Test Adapter between fuel rail and test port "Tee" on Fuel Line Pressure Test Adapter. If fuel system pressure does not fall below 30 psi (2.1 kg/cm2 ) for 5 minutes, fuel injector or fuel rail is leaking. Repair as necessary.

    2. Fuel Pump Check Valve, Filter/Regulator Check Valve Or Fuel Tube/Line Leakage

      Start engine and operate at idle for 2 minutes. Shut off engine. Clamp off rubber hose portion of Fuel Line Pressure Test Adapter between vehicle fuel line and test port "Tee" on Fuel Line Pressure Test Adapter. If fuel system pressure does not fall below 30 psi (2.1 kg/cm2 ) for 5 minutes, fuel rail and fuel injectors are not leaking. Check fuel lines and tubes for leakage.
    3. If fuel lines and tubes are okay, check electric fuel pump or filter/regulator check valves for leakage. A quick loss of fuel system pressure usually indicates defective check valve in the filter/regulator. A slow loss of pressure usually indicates a defective check valve in the electric fuel pump. Repair as necessary.
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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.