engine dies when at 1/4 tank,only if sitting on a tilt

Probably a bad fuel level sensor. A full tank is 17 gallons check your sensor by filling the tank when you are having these problems. A quarter tank should have about 4+ gallons left so if you can get in more than 14 gallons in it must be a bad sensor, gauge or sensor wiring. It could be water in the tank but if you are using gas with alcohol that should serve as a dry gas. If not then try putting dry gas in the tank.