Hi, I just picked up this vehicle and am receiving a DTC P0440. I discovered that it was a EVAP system malfunction. I started by checking the gas cap for any cracks or signs of wear in the gasket, all seemed fine.

I then physically checked the hoses from tank to charcoal canister, charcoal canister to vent solenoid, as well as from where you fill up to tank and everything looked ok.

After that I decided to remove and test both purge solenoid and vent solenoid with 12 volts and both appeared to be working fine.

I have also removed the charcoal canister and it was not heavy, nor did it have any sign of moisture in it.

I am at a loss as to what else to check. I have heard that maybe I should just take it to a shop and have them hook it up to a smoke machine, but have not done so yet. I am on a budget and not sure what they would charge for that.

Anyrate, any help out there would be greatly appreciated! Thanks in advance for you time!

 

https://blazerforum.com/forum/2nd-ge...de-p0440-7822/

 

Do the EVAP lines look rusty at all? The fuel filler tube is also prone to rusting through in vehicles from the north. A smoke test would reveal any leaks.

 

Just want to give an update on my progress with this problem....

I ended up having to replace my fuel pump...long story behind that, however it was a blessing in disguise...while I had the tank off, I noticed that the nipple on the fuel tank vent valve had been snapped off. I went to the local auto parts store and picked up a new vent valve for about $25. I also picked up about a foot and a half of the hose for it, now with the extra length on it, the fuel tank can sit on the ground before I have to disconnect the vent valve. Makes dropping the tank a lot easier! Anyrate, after reconnecting everything, no P0440 code!!! have been driving on it for about 3 weeks and has not come back... I think that may have done the trick!!
Thanks again for your help! Hopefully this will help someone else!