How to cut a trap door on 2000 silverado to access fuel pum

The easiest way to access the fule pump is to lift the bed or drop the tank. I have lifted the bed on many occasions. Just remove the bolts that hold it to the frame, but leave the two at the rear real loose, That way when you lift the front of the bed it will stay on the truck. Once it is lifted high enough, you can easily access the pump from the top of the tank. Cutting a "trap door" in the bed is not recommended as the sparks from cutting might ignite the gas fumes. Unless you take the bed off of the truck totaly, I wouldn't even attempt it.