How can my spider run so well when the tank is full, and then when it's low on fuel get a HUGE pressure in-tank build up, with poor performance? I've read all the pressurized fuel tank threads and tried chasing down all the fuel vapor lines, to no avail. Charcoal tank, check valve, one way intake, mini hoses to and from air filter and valve cover, all good. Changed the rear muffler although whenever I get this issue the gas tank is very hot to the touch. If I'm getting a hot tank and high pressure, what's the cause? Please, Alfisti AIUTO!