How to Change the Fuel Pump in a 3.8L Chevy Impala

Gasoline for the large 3.8L engine on your Chevy Impala is fed by a fuel pump located inside the fuel tank as part of the fuel sending unit assembly. You can access the assembly through the trunk of the car without the need to drop the tank. With all the necessary tools and replacement parts on hand, you may change the fuel pump in your Impala in a couple of hours.

Removing the Fuel Pump

Park your Impala on level ground in a well-ventilated area and open the hood.

Remove the sight shield from the top of the engine using a ratchet and socket, if equipped.

Loosen the fuel tank filler cap and disconnect the ground (black) battery cable with a wrench.

Locate the Schrader valve at the beginning of the fuel feed pipe on the fuel rail. This is the rail that feeds the fuel injectors. The valve is similar to the air valve on your Chevy tires.

Wrap a shop rag around the Schrader valve and depress the inside stem with a flat-head screwdriver. Use the rag to catch the fuel that will come out of the valve. After that, replace the sight shield to the top of the engine.

Take the spare tire and other items from the trunk of your Impala.

Remove the carpet from the trunk.

Unfasten the nuts from the fuel sender/pump access panel on the floor of the trunk and remove the access panel. Use a ratchet and socket.

Unplug the fuel tank pressure sensor and fuel sender from the assembly through the access hole.

Disconnect the hoses from the fuel sender/pump assembly. On hoses with plastic connectors, press the tabs and pull the hose from its fitting. On hoses with metal connectors, use tool set J 37088-A.

Rotate and unlock the retaining ring holding the fuel sender/pump assembly to the fuel tank using a drift punch and a hammer.

Lift the retaining ring and fuel sender/pump assembly out of the fuel tank. Locate the large O-ring seal between the fuel tank and the assembly and discard the O-ring.

Remove the fuel pump from the assembly using a pair of needle-nose pliers and a flat-head screwdriver.

Installing the New Fuel Pump

Mount the new fuel pump on the assembly using the pair of needle-nose pliers and flat-head screwdriver. Swing the float arm on the assembly and make sure the pump strainer is not in the arm’s way. Adjust it, if necessary.

Place a new assembly O-ring seal.

Insert the fuel sender/pump assembly into the fuel tank and verify that the pump strainer is not twisted. Then rotate the retaining ring with the drift punch and hammer to lock the assembly to the fuel tank.

Connect the hoses to the fuel sender/pump assembly by pushing the hose connectors against their fittings.

Plug the fuel tank pressure sensor and fuel sender to the assembly.

Tighten the fuel tank filler cap and connect the ground (black) battery cable using the wrench.

Turn the ignition to the “On” position for two seconds and then to the off for 10 seconds. Turn the ignition back to the “On” position and check for gas leaks around the tank.

Turn off the ignition.

Position the access panel in place and tighten the mounting nuts using the ratchet and socket.

Replace the carpet, spare tire and other items in the trunk.