I have searched this site and forum several time for an answer to why the rear saggs. The air pump pumps the rearend back-up every time -so far-. Why does the air escape from the bags and sometime it does not. Is there a check valve in line there. I have noticed that when I park the truck, if the front end is sitting several inches below the rear end the air bags remain pumped-up. When I bought the truck a year and a half ago this was not a problem. Any ideas?
