Lou, I confess to having a self interest in your problem, or should I say our mutual problem. I am getting the check engine light that my mechanic cleared and said if it comes on again, he will look more but the code was for a solenoid in the evaporative emissions system. He likes to wait on minor stuff before chargin in, that's why he has been my mechanic for over 20 years. Anyway, I also had the DIC check gas cap warning a few weeks before and it cleared when I adjusted the gas cap. The funny thing is that the check engine light has never come on when I am driving, only when technicians are driving - happened twice and both times some one else was driving. I Googled evaporative emissions check engine and found the problem is GM wide and also on some imports - the thing about our Vettes is some of the system is buried deep within the body. I think the canister (someone please chime in and help) is located on the rear starboard (passenger) side and that may be where the solenoid is. I also came across several instances of the plug to the solenoid being the problem so make sure it is not the plug. There is some procedure where they blow "smoke" in the evap emis system to see if there is a vacuum leak, the dealership was quick to suggest that. I called them because there was a statement that GM had an extended warranty on emissions systems that went to 80,000 miles and they do but it only covers the cat converter, SOL again.
So, I am hoping it is the solenoid that can be easily reached, or plug, and that cures the problem, otherwise to find a leak in the system, I think you will will have to pull the left rear wheel and take out the liner to get to the hoses that connect to the gas fill.
Sorry for the long winded rant, Please let me know what happens and I will do the same
Will
