I'm sorry. I didn't know there was any more posts about this. I was out of town and returned to "much fun". Anyway, getting caught up and reading."air vent on fuel cap open" - yes, in fact, I tried it once with the cap "open" (sitting on it, but not engaged)"Cover closed and latched". I don't have the supression kit on it. I have no other "covers" other than the rear shroud coving the flywheel. I think you are referring to the cover that is near the shroud over the oil filter area. I'll see if I even have that cover as I've noticed that I didn't have one on mine when looking at pics.Guyfang - i'll jump TB5-7 to TB5-9 and get the above noted cover (or fabricate one) and test.All - Thanks for responding. The sad thing is that I just got this setup to be back up power for my house, new breaker panel, interlock and all. Now i'm going to sell the house and build a new one. This time, in the country. Yes, the Gen is coming with me. So this is a good time for me to put some load on this so I can make sure it will handle the new construction. Needless to say, the new house will be built a bit more generator friendly. Again, sorry for the delay in responding.