[GySgtFrank]

Fuel slosh in the tank should not be a problem unless you're extremely low on fuel, which you have probably already checked. I would check your tank vent tube to make sure you're not getting a vacuum/over pressure condition in the tank and do a flow test on your pump. Check the wiring to the pump as well. I would think any of these would cause problems at other times than left turns only, but strange things happen. It makes no sense to me that it would only happen during left turns, unless you have a pump wire swinging over and grounding out during that condition. It is a common problem with carburetors as the fuel sloshes in the float bowls, but not with injection.

just throwing out ideas as it sounds like you're at wit's end.