I'v got a 2001 C5 with a P0442 code and have been trouble shooting for the "small" vacuum leak I have:

Replaced the fuel cap twice once with OEM and once with AutoZone (including not tightening to the first click)

Replaced the two hoses connecting the manifold to the purge valve and the valve to the rear line.

Disconnected the vacuum hose from the manifold and tested the diaphragm in the purge valve using a pump

Not sure if this works or not but put a vacuum gauge inline with the hose from the valve to the rear line, ran the engine and the gauge just vibrated between 0 and -10

Disconnected the hose going to the Canister in the engine compartment and tried pumping the line down, never even showed a vacuum.

My next job was to check the canister but been looking for the location of the evap canister, lots of diagrams but no real pictures with an exact location. is it behind something?

I know I could take it to the dealer but this car was a basket case when I first got it and I have nursed it back to drive ability, only three codes left. U1000 H, U1064 H
and P0442 besides don't like paying the Corvette Tax. And being retired with nothing but time I need the projects.

Thanks for any help and pictures if possible.

 

Moved over to C5 Tech.

 

Thanks Guys , yes I found it, to bad can't get to it easily.

JZ