Where is the fuel pump module located?

If you mean the control module that controls the low-pressure fuel pump, it is next to the spare tire in the rear of the vehicle. However, it is not a plug and play part, you need to be able to access the GM techline with the proper scan tool and pass through device in order to program the replacement module for the proper fuel flow for your vehicle.

Now if you mean the issue is the low-pressure fuel pump module itself, that is located inside the fuel tank. For that one you need to drop the tank down. Then blow all the accumulated dirt out from around the pump, disconnect the lines and wiring connectors and then remove the lock ring that secures the pump in the tank and remove it. Wipe the area around the gasket really well and use a new gasket (and if you are in a salt use area, buy a new lock ring with the new pump) and install the replacement pump.