That is really strange. I would test the fuel pressure at that angle, I would guess you can hear the pump going? Is it sucking air? don't forget there is a bowl in the tank to prevent the fuel pump from sucking air while in curves or angles, maybe that is defective. Overall a pressure test while at an angle that creates the problem will tell you a lot. Has the fuel filter been replaced regularly? That can weaken a pump, maybe it is just on it's way out.
Good luck!
Brian

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Brian W. Heitman

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