OK, I know the vapor canister threads have been beat to death and I'm pretty sure mine is toast...I have it out of the truck and by following the manual it says to apply low pressure ?psi to the tank line at that air should flow out both the purge and the bottom line. when I apply more than just what I can blow into it with a compressor at (+- 40 psi Per the FSM)I can hear the check ball slam closed and the can pressurizes....also it says that you should not be able to push air through the purge line at all but mine flows freely out the bottom. SO again I think it's toast and I have the GM plasic one on hand to replace....Here's the issue...when I run the truck at anything less than 1/2 to 3/4 tank I get a lot of pressure in the tank IE: when I remove the cap slowly it will off gas A LOT for 15-20 seconds...I thought at first that the vapor can was the issue but I even tried to pull the tank vent line off the vapor can after driving when I knew it was under pressure and it didn't off gas. I'm begining to wonder if that plastic valve in the tank under the vent fitting is the issue...This is a new OEM tank with all new hoses, pump, strainer, gaskets, cap and that valve thingy.....I also blew all the lines out with carb cleaner prior to installing the new tank so everything is clear. What do you guys think...Thanks in advance...
