2007 buick lacrosse will not restart after shutting it off to add fuel.

Could be, try spraying starting fluid into the intake, if it starts then its a fuel issue. It could also be bad gas. If there was water in the gas the water will sit at the bottom of your tank and gasoline engines can't run on water (diesels can).

Where is the relay switch located at on a Buick LA cross

You have a stuck open "fuel vapor solenoid" in the engine compartment. The fuel vapor line, from the gas tank to the emission's canister, is there for all of the vapors that are "stirred up" on refueling. Those vapors are sent from the tank to the canister (and held in the canister) while you are refueling. Then when you start the car, the fuel vapor solenoid "opens" and let those vapors go into the intake manifold. When that solenoid is stuck "Open", all of the fuel vapors go into the intake manifold, while you are fueling, and when you try to start the car, it acts like it's "flooded" - which it is with the vapors! Go on line, find out how to change the solenoid - is easy and cheap. Think I got the solenoid at Autozone or its competitor.

Where ir the water pump buick 2007 lacrosse?please