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Test NS-1B - Inspecting Fuel System

WARNING: This page is about a different car, the 1995 Dodge Ram Wagon, 1995 Dodge Ram Van, 1995 Dodge Pickup, and 1995 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
  1. Using scan tool, stop actuation test. Disconnect and inspect Compressed Natural Gas (CNG) low pressure sensor connector. Repair as necessary. Connect a jumper wire to CNG low pressure sensor connector between 5-volt power supply circuit (Violet/White wire) and CNG low pressure sensor signal circuit (Dark Green/Orange wire on AB body; Dark Green/Light Blue wire on AN and BR bodies). Using scan tool, read fuel pressure. If fuel pressure is less than 130 psi, go to step 6).
  2. If fuel pressure is more than 130 psi, check all fuel lines for kinks or restrictions. Repair kinks or restrictions. Perform TEST VER-1. If no kinks or restrictions are present, turn ignition off.
    NOTE: Before opening any part of Compressed Natural Gas (CNG) fuel system for repair, fuel pressure must be released. See FUEL PRESSURE RELEASE  .
  3. Release fuel pressure. If vehicle is equipped with fuel rail test port, connect a 0-300 psi fuel pressure test gauge to test port. On vehicles not equipped with fuel rail test port, remove Compressed Natural Gas (CNG) low pressure sensor. Connect a 0-300 psi pressure test gauge between CNG low pressure sensor and fuel rail block. Install CNG low pressure sensor to test gauge tee connection. If CNG low pressure sensor is not reinstalled, engine will start, then stall.
  4. On all models, using scan tool, actuate fuel system. If fuel pressure is more than 90 psi, release fuel pressure. Replace fuel pressure sensor. Perform TEST VER-1. If pressure is less than 90 psi, release fuel pressure. Replace fuel filter.
  5. Attempt to start engine. If engine starts, test is complete. Perform TEST VER-1. If engine does not start, replace fuel pressure regulator. Perform TEST VER-1.
  6. Remove jumper wire. Using scan tool in voltmeter mode, check voltage on CNG low pressure sensor connector, 5-volt power supply circuit (Violet/White wire). If voltage is less than 4.5 volts, repair open in Violet/White wire. Perform TEST VER-1. If voltage is more than 4.5 volts, turn ignition off.
  7. Disconnect and inspect Powertrain Control Module (PCM) connector. Repair as necessary. Perform TEST VER-1. If connector is okay, using scan tool in ohmmeter mode, check resistance of CNG low pressure sensor connector, CNG low pressure sensor signal circuit (Dark Green/Orange wire on AB body; Dark Green/Light Blue wire on AN and BR bodies). If resistance is less than 5 ohms, repair short to ground in Dark Green/Orange wire or Dark Green/Light Blue wire. Perform TEST VER-1. If resistance is more than 5 ohms, replace PCM. Perform TEST VER-1.
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