The part number oldblue shared is the part in the diagram that I asked you about.

 

#10 looks to be a molded o-ring.
#11 looks to be a plastic part with a nipple and small line that would go to it.

 

Number 6 is the solenoid. I don't see the seal in that diagram.
This video shows the solenoid being replaced and the rubber seal being installed

 

On the HHR there is no tube; the nozzle just sticks in the hole relying on the rubber seal. The picture catman posted is different from HHR.

 

5:14 of the video shows the seal.
I see it in the diagram as part of #5 tube assembly.
But yet Blue posted just a part number for the part needed.

 

#5 is the tube assembly with the gasoline filler neck and overfill vent tube

 

Been there done that. There is very little room between OD of the tube on solenoid and the ID of the tube it fits into. Any hose I could find that fit the OD of the solenoid was too thick to fit into the hose (#3 on the diagram). You are correct, it is something like 3/4 OD. As said, the parts you listed are for a Chevy/GMC full size 1500 truck so the hoses that come with that part won't work on the HHR. That evap valve is a very different animal from the HHR (I had to reaplce the one on my truck, so I've seen the difference). And both ends of the solenoid and tube (part #3) it fits into are made of hard plastic and can't be clamped. You can't buy that seal if your life depends on it.

I could not pass emissions because no matter what I did I still got a "Small Leak" code. I finally fashioned a washer of sorts to fit as snugly as possible in the small space. Then I used a small bead of silicone sealer around the gap. No more code, passed emissions. That was last March. It's been just fine since.

 

I am thinking I may have to try that myself. I have heat shrink tubing I was going to try and maybe some silicone

 

The seal p/N 22728655 is under $5.00, order it , if it’s the wrong part send me a PM , I’ll reimburse you if I’m wrong.

 

When I asked about this last year no one had a part #. If that's the part, that's great. I really can't understand why they can't simply include this with the replacement solenoid.

The heat shrink tubing is a great idea as an alternative.