Fuel Level Sensor

This procedure covers the removal and replacement of the fuel level sensor on a 2007 Ram 3500 with 5.9L Cummins diesel engine. The fuel tank must be lowered or removed to access the fuel pump module containing the sensor.

Warnings

Tools required

Parts

• Fuel level sensor × 1 — Use OEM specification or aftermarket equivalent for 2007 Ram 3500 diesel
• Fuel pump module seal/O-ring × 1 — Use OEM specification
• Fuel tank strap bolts (if corroded) × 4 — M10 x 1.5 grade 10.9

Preparation

1. Park vehicle on level ground and engage parking brake
2. Disconnect negative battery cable to prevent fuel pump activation
3. Relieve fuel system pressure by removing fuel pump relay and attempting to start engine until it stalls
4. If tank is more than 1/4 full, siphon fuel into approved containers to reduce weight and spillage
5. Raise and safely support vehicle on jack stands at frame rails, providing adequate clearance to lower fuel tank
6. Place transmission jack or fuel tank jack under center of fuel tank for support

Procedure

1. 1

   Disconnect fuel filler neck
   Locate the fuel filler neck connection at the front of the fuel tank. Loosen the hose clamp securing the filler neck to the tank using a flathead screwdriver or socket. Carefully work the filler neck off the tank inlet. If stuck, gently twist while pulling to break the seal.
2. 2

   Disconnect vent lines and EVAP lines
   Identify the fuel tank vent line and EVAP canister lines connected to the top of the tank. These are typically quick-disconnect fittings or hose clamps. Disconnect each line and move them aside. Label or photograph connections for reassembly reference.
3. 3

   Disconnect fuel lines from fuel pump module
   Locate the fuel supply and return lines connected to the fuel pump module on top of the tank. These use quick-disconnect fittings. Use the appropriate fuel line disconnect tool to release each fitting. Press the tool onto the line, then pull the line straight off. Have rags ready to catch residual fuel spillage.
4. 4

   Disconnect electrical connector
   Locate the electrical connector for the fuel pump module on top of the tank. Press the release tab and carefully disconnect the connector. Ensure the connector is moved away from the work area to prevent damage.
5. 5

   Support and lower fuel tank
   Ensure the transmission jack or tank jack is securely positioned under the center of the fuel tank. Locate the fuel tank strap bolts (typically one per strap; verify count on this vehicle). Using the appropriate socket, remove the strap bolts while supporting the tank weight with the jack. Carefully lower the straps away, then slowly lower the tank 6-8 inches to access the top of the fuel pump module. Do not fully remove the tank unless necessary.
6. 6

   Clean fuel pump module area
   Using shop rags and a parts brush, thoroughly clean the top of the fuel tank around the fuel pump module lock ring. Remove all dirt, debris, and corrosion to prevent contamination from entering the tank during disassembly.
7. 7

   Remove fuel pump module lock ring
   Using the fuel pump module lock ring spanner tool, rotate the lock ring counterclockwise to unlock. If the tool is not available, use a brass punch and hammer to carefully tap the lock ring tabs counterclockwise. Never use steel tools that could create sparks. Once loosened, remove the lock ring completely.
8. 8

   Remove fuel pump module assembly
   Carefully lift the fuel pump module assembly straight up and out of the tank opening. The assembly includes the fuel pump, fuel level sensor float arm, and associated components. Tilt the assembly slightly to maneuver the float arm and fuel level sensor out of the tank opening without damaging components. Have rags ready to catch dripping fuel. Place the assembly on a clean work surface.
9. 9

   Remove old fuel level sensor
   Inspect the fuel pump module assembly to locate the fuel level sensor. The sensor is typically mounted to the side of the module with a float arm attached. Disconnect the electrical connector from the sensor to the module. Remove the retaining clips or screws securing the sensor to the fuel pump module housing. Carefully slide the fuel level sensor and float arm assembly off the module.
10. 10

    Install new fuel level sensor
    Compare the new fuel level sensor with the old unit to verify correct replacement part. Install the new sensor onto the fuel pump module housing, ensuring the float arm moves freely through its full range of motion without binding. Secure with retaining clips or screws. Connect the electrical connector from the sensor to the module, ensuring it clicks into place securely.
11. 11

    Inspect and replace O-ring seal
    Remove the old O-ring seal from the top of the fuel tank opening and discard. Clean the sealing surface on the tank thoroughly. Install the new O-ring seal into the groove on the tank opening, ensuring it seats properly and is not twisted or damaged.
12. 12

    Reinstall fuel pump module
    Carefully lower the fuel pump module assembly back into the fuel tank opening, maneuvering the float arm and sensor to avoid damage. Ensure the module is properly oriented with alignment marks or tabs. Press the module down until it seats fully against the O-ring seal.
13. 13

    Install lock ring
    Place the lock ring over the fuel pump module and hand-thread it clockwise until it contacts the tank. Using the lock ring spanner tool or brass punch, tighten the lock ring firmly clockwise until the tabs reach their stops. Ensure the lock ring is fully seated and the module is secure.
14. 14

    Raise and secure fuel tank
    Using the transmission jack, carefully raise the fuel tank back into position against the vehicle underbody. Align the fuel tank strap mounting points. Install both fuel tank straps and start all four strap bolts by hand. Tighten the strap bolts evenly in a cross pattern to secure the tank firmly without deforming it. Inspect for proper tank positioning.
15. 15

    Reconnect all connections
    Reconnect the fuel pump module electrical connector until it clicks. Reconnect the fuel supply and return lines, pushing them onto the module fittings until they click into place. Tug each line to verify secure connection. Reconnect all vent lines and EVAP lines. Reconnect the fuel filler neck to the tank inlet and secure with the hose clamp.

Reassembly

1. Verify all fuel lines are properly connected and secured with no kinks or damage
2. Verify all electrical connections are secure and connectors are fully seated
3. Reconnect negative battery cable
4. Install fuel pump relay back into fuse box

Verification

• Turn ignition to ON position (without starting) and listen for fuel pump to run for 2-3 seconds, priming the system
• Check for fuel leaks at all connection points, especially at the fuel pump module and fuel lines
• Cycle ignition OFF and ON three times to fully prime the fuel system before starting
• Start engine and verify it runs smoothly without fuel starvation or hesitation
• Check fuel gauge operation by observing current fuel level matches expected level based on amount in tank
• Using a scan tool or instrument cluster, verify fuel level sensor reading is accurate and responds to fuel level changes
• Take a short test drive and recheck all connections for leaks
• Monitor fuel gauge for proper operation over the next several days of driving

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