PO442 EVAP small leak

AJCUSTOMS

MEMBER
2005 GMC ENVOY
89,000 MILES

Already replaced the purge valve and also the vent valve. Put a hundred miles on it pop back on again. I know I'm looking at the filler neck which looks like it has moisture areas from gas leaking. Have you guys ever heard of anything from these filler necks? Because this is looking kind of crummy to me. I do not have access to a smoke machine and as I've said in the past I am a dealership tech that is retired 35 years of twisting wrenches. So I have a fair idea of what I'm doing. The gas cap has also been changed with a factory OEM cap as I said then they're done. This I just wanted to know if you guys have any more input on this if the purge canister the saint known for cracking or if there is a problem with these next rotting and putting? Especially underneath the flexible area where the hose goes to connect the two next the one from the tank to the one to the body. Please get back to me as soon as possible and let me know. I would appreciate any input on this subject. Thank you, AJ from AJ customs

Saturday, November 16th, 2019 AT 1:37 PM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

I attached the test just in case you need it. However, you are correct that a smoke machine would help. But you can also do this with a vacuum pump. You have to separate the system into sections but these lines and components should hold a vacuum because they do hold the pressure from the fuel heating and cooling. All this code is saying is that the pressure in the tank did not drop the proper amount of pressure when the key was shut off. Meaning it dropped to fast so it assumes there is a leak.

If this is the case, then if we put a vacuum on these parts then it should hold a vacuum. However, just make sure you split the system up because unless you are using a large vacuum machine, it will take too long to pull it down. So just cap your lines and test it. You may have to squeeze the lines a little because if they are cracked then they will not leak all the time.

As for the components you mentioned. I have not seen an issue with these over the years however, anywhere your tank is holding pressure is your issue which means the filler neck could be part of the issue depending on where your close off valve is.

Images (Click to make bigger)