Hi everybody, I recently bought a 2002 Chevy Trailblazer LTZ. 4.2 straight 6 cylinder. 177,000 miles.
Anyway, I passed the safety inspection but failed emissions with a code set of P0440, Large Evap leak. I visually checked everything I could get to and didn't notice anything right off the bat. I replace the vent and purge valves. also replaced the gas cap because it had a bad O-ring seal. still set code.
I took all the connectors off and cleaned etc, but the O-rings in the evap lines looked kinda flat, and when pushing them back on they felt kinda loose.
I'm going to do a smoke test tonight or tomorrow.
My question is, can I replace just the O-rings in the evap lines? I'm not sure I can find new lines, though I haven't looked to hard yet.
I'll let you know how the smoke test goes. thanks!

You can get just the O-rings, but the smoke test will tell you where to look before you go through all of that.

thanks, going out to do it in an little while.

went out to do the smoke test and noticed the schrader valve was loose on the test port. I hadn't checked it before because I thought it was a fuel line. Duh. Anyway, when I tried to tighten it it just spun. So I put the hose for the smoke thing right over the threads where the cap goes on, it fit nice and snug. I put smoke into the system and looked around and didn't see any coming out anywhere.
BUT... I forgot to ground the vent valve to close it. another DUH! Would that screw up my test? If so I can do another one tomorrow, it was pretty easy.
And I also got the pressure up to about 10 psi. Would that damage anything? I used a bicycle pump.
opinions please. and many thanks.

You should have a flow meter that lets you know it'* charging the system with smoke. I'm not sure it took any. What kind of machine?

the fact that I used a bicycle pump should give it away . I made it from a video on YouTube. It blows out plenty of smoke.
what about the vent valve?

Good luck with that.

not everybody can afford a $100+ smoke machine. if I had money I'd take it to a dealer. what the hell do you think this forum is for!
Does anyone else care to help me???

The valve that spins loosely probably leaks.

I wouldn't put 10PSI to any part of the fuel and system unless it is by using the fuel pump connected properly.

thanks CathedralCub but I'm working on an evap leak. Did you mean evap and not fuel? I'm gonna try and find a new valve ASAP. But right now I have no idea where to get one. I have a bunch of schrader valves for AC but they are all different sizes. I'll let you all know what I find.