if you just had the fuel pump replaced they probably have done something that caused the p0440. easy enough to do accidently like you said takes 3 days to come on sometimes. probably a loose or cracked hose or a bad o-ring on an evap canister line. maybe even the large o-ring that seals the top of the tank around the fuel sender.

 

the p-0440 code also had came on my 2002 monte carlo , i replace the gas cap , the purge solenoid on top of the motor , and the other piece by the tank but the check engine light is still on so whats the next step anybody took to turn the damn light off lol.....please someone help me.

 

Have it smoke tested for leaks?

 

ok thanks i will go ahead and have done , and i will let you know if it works or not.....thanks again for your help.

 

Someone correct me if I'm wrong... But don't you need to get the code reset? The problem may be fixed, but the check engine light won't go away 'til the code is reset, right? If so, you can have the code reset at most auto parts stores.

 

yes i did reset the code , the check engine light went off than came back on again, sorry if you miss understood my post lol.....

 

Sorta.
The emissions codes will clear when the car goes through three passing cycles of the check that caused the code to trip.

 

My 01 has a short vacuum hose at the purge vale solenoid with a sharp U-turn bent. I found the hose cracked at the sharp bend and that fixed the code problem.