Fuel Pump Module

This procedure covers removal and replacement of the fuel pump module (lift pump) on a 2007 Ram 3500 with 5.9L Cummins diesel engine. The lift pump supplies low-pressure fuel from the tank to the injection pump.

Warnings

Tools required

Parts

• Fuel pump module assembly × 1 — Verify compatibility with 2007 5.9L Cummins diesel
• Fuel pump module seal/O-ring × 1 — Usually included with pump module

Preparation

1. Park vehicle on level, solid surface with parking brake engaged and transmission in Park
2. Ensure fuel tank is no more than 1/2 full to minimize spillage. If tank is fuller, consider siphoning fuel or driving to reduce fuel level
3. Position Class B fire extinguisher within immediate reach of work area
4. Disconnect negative battery cable to eliminate electrical ignition sources
5. Allow engine to cool completely if recently operated
6. Gather all tools and parts before beginning work
7. Put on fuel-resistant nitrile gloves and safety glasses

Procedure

1. 1

   Relieve fuel system pressure
   On the diesel lift pump circuit the fuel pressure is relatively low. With the negative battery cable already disconnected per preparation, the lift pump will not run and residual pressure will bleed down. Simply plan for fuel spillage when the lines and module are opened; there is no need to run the engine to stall..
2. 2

   Raise and support vehicle
   Raise and support the vehicle securely on jack stands rated for its weight at the manufacturer-specified frame jacking points. Because the fuel pump module is in-tank, prepare to support and lower the fuel tank (using a transmission jack) to gain access to the module on top of the tank; drain the tank to a low level first to reduce weight and spillage. Ensure vehicle is stable and level before working underneath. Never rely solely on hydraulic jack.
3. 3

   Locate fuel pump module
   On the 2007 Ram 3500 with the 5.9L Cummins, the fuel pump module (electric lift pump combined with the fuel level sending unit) is an in-tank assembly mounted in the top of the fuel tank and retained by a lock ring. Access requires lowering or removing the fuel tank to reach the module on top of the tank, not the frame rail. Clean the area around the module opening thoroughly before removal to prevent dirt from entering the fuel system. It is a cylindrical module with fuel lines attached. Clean area around pump with wire brush and shop towels to prevent dirt from entering fuel system during removal.
4. 4

   Disconnect electrical connector
   Locate the electrical connector on the fuel pump module. Press release tab and pull connector straight off pump. Inspect connector for corrosion or damage. If connector is corroded, clean terminals before reassembly.
5. 5

   Position catch pan and disconnect fuel lines
   Position catch pan directly beneath fuel pump module to capture fuel spillage. Using fuel line disconnect tools, depress the quick-connect fittings at the top of the fuel tank module and separate the fuel supply and return lines. Label the lines to ensure correct reconnection. Expect significant fuel spillage from lines and pump. Cap or plug open lines if available to minimize spillage and contamination. If using quick-disconnect tools, ensure tool is fully inserted around line before attempting to separate connection.
   ⚠Fuel will spray when lines are disconnected. Point line openings into catch pan and away from face and body.
6. 6

   Remove pump mounting hardware
   Rotate the module lock ring counterclockwise using a fuel pump lock ring tool (or carefully with a brass punch and hammer) to release the module retaining ring. Lift the fuel pump module straight up out of the tank, tilting slightly to clear the float arm, and allow residual fuel to drain into the catch pan. Carefully lower pump assembly and allow remaining fuel to drain from pump into catch pan.
7. 7

   Inspect and clean mounting area
   Inspect mounting bracket and frame rail for corrosion, cracks, or damage. Wire brush mounting surfaces to remove dirt, rust, and old seal material. Wipe clean with shop towels. Check fuel line routing and condition while pump is removed. Look for abrasion, cracks, or fuel leaks along entire line length.
8. 8

   Prepare new fuel pump module
   Remove new fuel pump module from packaging. Verify it matches original pump configuration and has correct inlet/outlet port orientations. Install the new tank seal/O-ring into the fuel tank flange opening (or onto the module flange) as provided. Lightly lubricate the seal with clean diesel fuel (not petroleum jelly or other lubricants) to ease installation. Do not over-tighten or damage O-ring during installation.
9. 9

   Install new fuel pump module
   Lower the new fuel pump module straight into the fuel tank opening, orienting it to the tank's alignment marks and taking care not to bend the fuel level float arm. Seat the module flush against the seal, then install and rotate the lock ring clockwise using the lock ring tool until it locks into position. If torque specification is available from manufacturer instructions, apply specified torque. Otherwise, tighten bolts firmly to secure pump without over-torquing.
10. 10

    Reconnect fuel lines
    Reconnect fuel supply line from tank to pump inlet. Push quick-connect fitting straight onto pump port until it clicks and locks. Tug gently on line to verify secure connection. Repeat for fuel outlet line to engine. Ensure both connections are fully seated and locked. Verify no interference between fuel lines and driveshaft, exhaust, or frame components.
11. 11

    Reconnect electrical connector
    Plug electrical connector onto fuel pump module. Push firmly until connector locks with audible click. Tug gently to verify secure connection. Ensure wiring harness is routed away from heat sources and moving components.
12. 12

    Lower vehicle and reconnect battery
    Remove jack stands and carefully lower vehicle to ground. Reconnect negative battery cable to battery. Ensure cable terminal is tight and secure.
13. 13

    Prime fuel system
    Turn ignition key to ON position (without cranking engine) for 10-15 seconds to activate fuel pump and prime system. Turn key OFF and wait 10 seconds. Repeat this cycle 4-5 times to fill fuel lines and injection pump with fuel, bleeding air from system. This prevents prolonged cranking on initial start.

Reassembly

1. All fuel line connections must click and lock positively. Verify by tugging on lines.
2. Electrical connector must be fully seated and locked to ensure pump operation.
3. Ensure no tools or rags are left in work area before starting engine.
4. Dispose of fuel-soaked rags in sealed metal container away from heat sources.

Verification

• Start engine and verify it starts within normal cranking time (may take slightly longer on first start due to air in system)
• With engine running at idle, inspect all fuel line connections at pump for leaks. Look for wet spots, drips, or fuel odor
• Raise engine RPM to 1500-2000 RPM briefly and recheck for leaks under higher fuel pressure
• Verify no fuel drips from pump mounting area or connections onto ground
• Listen for unusual noises from fuel pump (whining, grinding, or cavitation sounds indicate problem)
• Test drive vehicle to verify normal operation under load. Engine should accelerate smoothly without hesitation or loss of power
• After test drive, perform final inspection underneath vehicle for any new fuel leaks that may appear after system pressurizes fully
• Monitor fuel system operation over next several days for any signs of leaks, low power, or starting difficulties

More procedures for this vehicle