If your on an 04, the Fuels tend to have a problem with leaks coming from where the valves are glued to the actual bladder. This is a manufacturing fault as the glue that is used doesn't stick as well to the black valves that the 04 kites have (thats why all the 05 kites have clear ones like most other brand kites, the clear ones bond better to the bladder) If you get a leak on any of the valves take it to the place of purchase, or email slingshot direct & the should send you out a replacement bladder (the ones their using in the 05 kites)
The pressure for the Fuels should be approx 6psi.