Can't fill up. Evap question
 

I'm getting an evap malfunction code for about a week now and last night I couldn't put gas in my car. Would the purge solenoid or the vent valve cause this? If the purge valve is under the hood, where is the vent valve and how do I get to it? Is the charcoal canister hard to change while I'm at it?

What year is your car?

This matters because vent valve and canister location are different for the '98 tank vs. the '99+ tank. Purge valve is in the same location for all.

This problem seems to pop up from time to time. I know that some people with this issue only seem to encounter the refueling problem when they let the tank get to or below ~1/4 or so. Some have also found that they can relieve tank pressure by sticking a metal rod (like a coat hanger) down the fill tube, though this can also lead to a spray of gas if you have already tried to put fuel in and it's backed up in the fill tube above the blockage point.

There are several threads I've seen on this over the years. If you do a search, you'll find more details. Here is one thread that I saved a link to many years ago, you might find it helpful:

https://ls1tech.com/forums/southern-...take-fuel.html

It's a 2002 ss. I tried filling up last night and it puddled up at the top. This morning it had drained down. I think the code was p0440 if that helps.

The canister vent is on top of the tank. GM's are bad about their canister vent's clogging up. When you drop the tank make sure you check the lines. A collapsed vacuum line will cause the same problem.