P0440 GMC -

Question

Purge valve has been changed as well as a new fuel pump instaled

Answer 1

P0440 Evaporative emission control system malfucntion

Fuel cap can cause this code, the Fuel pressure sensor not reporting properly can cause this code. poor sealing at the fuel pump, leak at the fuel filler neck. poor connection to the EVAP vent solenoid. Doing a visual inspection for any loose hose clamp for the fuel area especially when the fuel tank was removed