Fuel Level Sensor

This procedure replaces the fuel level sensor (sending unit) in the fuel tank of a 1994-2007 Dodge Ram 2500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Fuel level sensor/sending unit × 1 — Use OEM Mopar specification or equivalent
• Fuel tank lock ring seal × 1 — Use OEM specification
• Fuel line O-rings × 2 — Use OEM specification

Preparation

1. Park vehicle on level ground and apply parking brake. Chock front wheels securely.
2. Disconnect negative battery cable to prevent electrical sparks during fuel system work.
3. Relieve fuel system pressure by loosening fuel filler cap to vent tank pressure.
4. If tank is more than 1/4 full, siphon fuel into approved fuel storage containers using fuel siphon pump.
5. Raise rear of vehicle with floor jack and support securely on jack stands rated for vehicle weight. Ensure vehicle is stable before working underneath.
6. Allow exhaust system to cool completely if vehicle was recently operated.

Procedure

1. 1

   Access fuel tank and disconnect electrical
   Locate the fuel tank mounted under the vehicle bed (position varies by cab/bed configuration — typically driver side or center; verify for your specific model). Locate the fuel level sensor electrical connector on top of the tank. Disconnect the electrical connector by pressing the release tab and pulling straight apart. Clean area around connector to prevent contamination.
2. 2

   Disconnect fuel filler neck
   Locate the rubber fuel filler neck hose connecting to the fuel tank. Loosen the hose clamp securing the filler neck to the tank using appropriate socket. Slide clamp back on hose and carefully twist and pull filler neck off the tank inlet pipe. Be prepared for residual fuel spillage.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
3. 3

   Disconnect fuel lines
   Locate the fuel supply and return lines at the front of the fuel tank. Identify the fuel supply and return line fitting type (quick-connect, banjo, or clamped hose — this varies by model year across 1994-2007). For quick-connects, use fuel line disconnect tools by pressing the tool into the fitting while pulling the line away from the tank. For banjo/threaded fittings, loosen with a flare-nut wrench and replace sealing washers. Place drain pan underneath to catch fuel spillage. Cap or plug open lines to prevent contamination.
   ⚠Residual fuel pressure may still be present. Point line ends into drain pan during disconnection.
4. 4

   Disconnect vent line
   Locate and disconnect the fuel tank vent line from the top or side of the fuel tank. This may be a rubber hose secured with a clamp or a quick-connect fitting. Loosen clamp or use disconnect tool as appropriate.
5. 5

   Support and lower fuel tank
   Position a floor jack with a wide piece of wood under the center of the fuel tank to support its weight. Locate the fuel tank strap mounting bolts (verify count and location for your model year — typically each strap is bolted at one end and hooked/hinged at the other). Support the tank before loosening. Using a socket and ratchet, slowly loosen (but do not remove) the strap bolts evenly while supporting tank weight with jack. Lower the jack gradually to lower the front of the tank approximately 6-8 inches for access to the top of the tank.
   ⚠Tank may contain 15-20 gallons of fuel even when gauge reads 1/4 full. Tank weight with fuel can exceed 150 lbs. Use adequate jack support.
6. 6

   Remove fuel level sensor lock ring
   Clean the top of the fuel tank around the fuel level sensor lock ring to prevent debris from entering tank. Using the fuel tank lock ring tool, rotate the lock ring counterclockwise to release it. Note: Mopar sending units typically use a cam-lock ring that rotates only a partial turn to release rather than fully unthreading — verify the lock ring style before applying force. If stuck, tap the tool gently with a brass punch or non-sparking hammer. Remove lock ring completely and set aside with seal.
7. 7

   Remove fuel level sensor assembly
   Carefully lift the fuel level sensor assembly straight up and out of the tank opening. Tilt the assembly at an angle to navigate the float arm through the opening without damage. Be prepared for fuel to drain from the assembly. Place the old assembly in a drain pan. Remove and discard the old lock ring seal from the tank opening.
8. 8

   Inspect and clean tank opening
   Inspect the fuel tank opening for debris, rust, or damage. Use a clean shop rag to wipe the sealing surface on top of the tank where the lock ring seal seats. Check that the tank opening is free of debris that could fall into the tank.
9. 9

   Install new fuel level sensor
   Install the new lock ring seal onto the fuel tank opening, ensuring it is seated properly in the groove. Carefully lower the new fuel level sensor assembly into the tank opening at an angle to clear the float arm. Rotate the assembly to align the mounting tabs with the slots in the tank opening. Press the assembly fully down until it seats against the seal.
10. 10

    Install and tighten lock ring
    Position the lock ring over the fuel level sensor assembly, aligning the threads. Using the lock ring tool, rotate the ring clockwise until it locks into position, pulling the sensor assembly tight against the seal so it cannot rotate. Note: if this is a cam-lock ring, it engages with a partial clockwise turn rather than threading on — do not force it.
11. 11

    Raise and secure fuel tank
    Using the floor jack, carefully raise the fuel tank back into its original position under the vehicle. Align the fuel tank straps with their mounting brackets. Install and tighten the fuel tank strap mounting bolts to specification, alternating between sides for even support.
12. 12

    Reconnect fuel lines and filler neck
    Install new O-rings on the fuel line fittings. Reconnect the fuel supply and return lines to the tank, pushing each line firmly into its quick-connect fitting until you hear or feel a click. Tug on each line to verify secure connection. Reconnect the vent line and secure with clamp if applicable. Slide the fuel filler neck hose onto the tank inlet pipe and position the hose clamp. Tighten the clamp to specification.
    ℹ️Ensure O-rings are properly seated before tightening fittings to prevent fuel leaks.
    Torque spec

    Fuel Line Fittings25 Nm (18 lb-ft)

    Hose Clamps3 Nm (2 lb-ft)
13. 13

    Reconnect electrical connector
    Reconnect the fuel level sensor electrical connector, ensuring it clicks into place securely. Verify the connector lock tab is fully engaged.

Reassembly

1. Reconnect the negative battery cable to restore electrical power.
2. Lower vehicle from jack stands carefully and remove jack stands and chocks.
3. Add fuel to tank if it was siphoned during the procedure.

Verification

• Turn the ignition key to the ON position (without starting engine) and verify the fuel gauge responds and shows appropriate fuel level.
• Start the engine and allow it to idle. Inspect all fuel line connections, tank filler neck, and lock ring area for fuel leaks. Address any leaks immediately.
• Turn off engine and inspect again for leaks after fuel system pressure stabilizes.
• Test drive vehicle and verify fuel gauge operates correctly through various fuel levels by monitoring gauge movement during normal operation.
• After test drive, perform final inspection underneath vehicle for any fuel leaks or loose connections.

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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