You better feel up your relay first!!! If she's hot, -that's what may be failing. Quickest way to tell is see if it's hot to the touch. Don't let that fool you into a new pump.
I maintenance my pump and shoot, I could have the pump changed out and the tank ready to be raised in place by the time you get all those bed bolts out. Bed mount bolts can either go real easy or can be a PITA. Usually a PITA on anything w/miles behind it.
Quickest way to drain the fuel:
Crawl under the truck with a can of WD40, pliers (long pre-bent needle nose works best/45 degree bend),small skinny screw driver and one larger type. Squeeze the rear vent hose clamp together and slide it up the hose. Now douse the rear vent and vent hose w/WD40. Work it in a bit/ use small screw driver to get under the vent hose and hit it again w/WD40. The vent hose will pull off and when you turn the rear tank vent counter clockwise, - it will pull right out. Remove existing Petrol.
Use this procedure on remaining vents up top after lowering the tank a little. It's easier. DEFINITELY use WD40 on top or you'll end up getting cheesed off and breaking crap. - Trust me, you will break stuff without and don't even think about removing the bed.
If you jack it up (non 4x4 only), try to keep it level. You only need one floor jack for the tank, you can balance it fairly easy.