Fuel Pump Module

This procedure covers the removal and replacement of the fuel pump module assembly on a 2014-2018 Chevrolet Silverado 1500 with the 5.3L V8 EcoTec3 engine, accessed through the in-bed service cover.

Warnings

Tools required

Parts

• Fuel pump module assembly × 1 — AC Delco MU2390 or equivalent
• Fuel pump module O-ring seal × 1 — Use OEM specification
• Fuel line quick-connect O-rings × 2 — Use OEM specification

Preparation

1. Park vehicle on level ground outdoors or in a well-ventilated area. Ensure no ignition sources are present within 50 feet.
2. Verify fuel tank is less than 1/4 full. If over 1/4 tank, drain fuel using approved equipment into appropriate containers.
3. Disconnect negative battery cable and wait 2 minutes to allow electrical systems to discharge.
4. Remove cargo from truck bed and ensure access to bed floor above fuel tank (driver side, forward of rear axle).
5. Place fire extinguisher within immediate reach of work area.
6. Put on fuel-resistant nitrile gloves and safety glasses.

Procedure

1. 1

   Relieve fuel system pressure
   Locate the fuel pump fuse in the underhood fuse block (check owner's manual for exact location, typically labeled 'Fuel Pump'). Remove the fuel pump fuse. Attempt to start the engine; it should start briefly then stall as residual fuel pressure is depleted. Crank the engine 2-3 additional times to ensure all pressure is relieved. Turn ignition off. Alternatively, if equipped with a GDS2 scan tool, use the fuel pump control module depressurization function.
   ⚠️Do not skip this step. Residual fuel pressure can cause fuel to spray forcefully when lines are disconnected.
2. 2

   Access fuel pump module cover
   Locate the rectangular fuel pump access cover in the truck bed floor on the driver side, forward of the rear axle. Clean the area thoroughly around the access cover to prevent debris from entering the fuel tank. Remove the access cover screws using a socket or screwdriver. Carefully lift the access cover and foam insulation pad to expose the fuel pump module.
   Torque spec

   Access Cover Screws5 Nm (4 lb-ft)
3. 3

   Disconnect fuel pump electrical connector
   Locate the electrical connector on top of the fuel pump module. Press the locking tab and carefully pull the connector straight up to disconnect. Inspect the connector for corrosion or damage. If corrosion is present, clean with electrical contact cleaner and allow to dry completely before proceeding.
   ⚠Do not pull on wires. Pull only on the connector body to avoid damaging the harness.
4. 4

   Disconnect fuel supply and EVAP lines
   Identify the fuel supply line (larger diameter, typically black) and EVAP vent line (smaller diameter) connected to the top of the fuel pump module. Place shop towels around the connections to catch residual fuel. Using the appropriate fuel line disconnect tool, depress the retaining tabs and pull the lines straight off the module fittings. Cap or plug the lines to prevent contamination. Inspect the quick-connect fittings for damage and note that new O-rings will be required during reassembly.
   ⚠Expect a small amount of fuel to drain from the lines. Have absorbent towels ready and dispose of fuel-soaked materials properly.
5. 5

   Remove fuel pump lock ring
   Using the fuel pump lock ring tool (J-45722 or equivalent), engage the tool with the lock ring tabs. The lock ring threads clockwise to tighten and counterclockwise to loosen (reverse thread on some models - verify direction before applying force). Carefully turn the lock ring counterclockwise to loosen. If the lock ring is seized, tap the tool gently with a plastic mallet while applying turning pressure. Once loose, remove the lock ring completely by hand.
   ⚠Do not use a hammer and punch to loosen the lock ring. This can create sparks and damage the lock ring threads or fuel tank flange.
6. 6

   Remove fuel pump module assembly
   Carefully lift the fuel pump module straight up and out of the fuel tank opening. Tilt the module slightly to angle the fuel level sender arm through the opening. The module will contain residual fuel - be prepared with a drain pan. Once clear of the tank, place the module in the drain pan and allow fuel to drain completely. Note the orientation of the module for proper installation of the replacement unit.
   ⚠The fuel level sender float arm extends from the bottom of the module and can be easily damaged. Handle carefully to avoid bending.
   ⚠️Several ounces of gasoline will drain from the module. Ensure adequate ventilation and keep drain pan away from ignition sources.
7. 7

   Inspect fuel tank and prepare new module
   Using a flashlight, inspect the inside of the fuel tank opening for debris, sediment, or contamination. If excessive debris is visible, the tank should be removed and cleaned professionally. Remove the old O-ring seal from the fuel tank flange and clean the sealing surface thoroughly with a lint-free cloth. Remove the new fuel pump module from packaging and verify it matches the original configuration. Install the new O-ring seal onto the fuel tank flange (not on the module). Lightly lubricate the O-ring with clean engine oil or petroleum jelly.
   ℹ️Do not reuse the old O-ring. A failed seal will cause fuel odor in the cabin and potential fuel leakage.
8. 8

   Install new fuel pump module
   Carefully lower the new fuel pump module into the fuel tank opening, tilting as necessary to fit the fuel level sender arm through the opening. Align the module so that the fuel supply and EVAP fittings point toward the front of the vehicle (or match the orientation of the original module). Press the module down evenly onto the O-ring seal, ensuring it seats completely against the tank flange. Verify the module is oriented correctly before proceeding.
   ⚠Do not force the module. If it does not seat easily, remove and check for obstruction or misalignment of the fuel level sender arm.
9. 9

   Install and torque lock ring
   Place the lock ring over the fuel pump module and engage the threads on the tank flange. Hand-tighten the lock ring clockwise until it contacts the module flange. Using the fuel pump lock ring tool and torque wrench, tighten the lock ring to the specified torque. Ensure the lock ring seats evenly around the entire circumference of the module.
   ⚠Over-torquing can damage the lock ring or tank threads. Under-torquing can allow fuel leakage. Use a calibrated torque wrench.
   Torque spec

   Fuel Pump Lock Ring85 Nm (63 lb-ft)
10. 10

    Reconnect fuel lines and electrical connector
    Install new O-rings on the fuel supply and EVAP line quick-connect fittings. Lightly lubricate the O-rings with clean engine oil. Push each line firmly onto its corresponding module fitting until you hear and feel a distinct click, indicating the retaining mechanism has engaged. Gently pull on each line to verify it is locked in place. Reconnect the fuel pump electrical connector, pressing firmly until the locking tab clicks into place.
    ⚠Improperly connected fuel lines will leak under pressure. Always verify the connection is secure by pulling on the line.
11. 11

    Reinstall access cover
    Position the foam insulation pad over the fuel pump module assembly. Place the access cover over the insulation, aligning the screw holes. Install the access cover screws and tighten to specification in a crisscross pattern to ensure even sealing.
    Torque spec

    Access Cover Screws5 Nm (4 lb-ft)
12. 12

    Restore power and prime fuel system
    Reconnect the negative battery cable. Reinstall the fuel pump fuse. Without starting the engine, turn the ignition key to the 'ON' position for 2 seconds, then 'OFF' for 10 seconds. Repeat this cycle 3-4 times to allow the fuel pump to prime the system and build pressure. Check all connections under and around the access cover for signs of fuel leakage.

Reassembly

1. Access cover screws must be tightened in a crisscross pattern to ensure even compression of the seal.
2. New O-rings must be installed on all fuel line connections - never reuse old O-rings.
3. Verify all quick-connect fuel line fittings are fully seated and locked before pressurizing the system.

Verification

• With the ignition in the 'ON' position (engine not running), listen for the fuel pump to activate for approximately 2 seconds. The pump should run smoothly without unusual noise.
• Inspect the fuel pump access cover area and all line connections for fuel leakage while the pump is priming.
• Start the engine and allow it to idle. Check for fuel leaks around the access cover and monitor for smooth idle quality. The engine should start normally without extended cranking.
• Verify the fuel gauge reads accurately by comparing to known fuel level. If the gauge is inaccurate, recheck module installation orientation.
• Test drive the vehicle and monitor for proper fuel delivery, normal engine performance, and absence of fuel odor in the cabin.
• After test drive, recheck all connections for leakage and verify no check engine light or fuel system codes are present.

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