hi
if it is the pump they are cheap, like $30. Bad news is its a PITA to get out. Have to drop a 32 gallon fuel tank full of fuel and usually the bolts are rusted. I cursed at mine for 3 hours just to get the skid plate loose.
Then called a friend for suggestions. I still owe him a beer for this. Took 20 minutes and did not have to drop the tank.
take an old towel or some rags soak them in water and stuff them between the top of the fuel tank and the body. Then take a small drill like 1/4 or smaller. Climb into the bed and try to get about where the fuel sender is. Drill a small hole. Go slow you want to go through the sheet metal of the floor, Not into the tank!!
The wet towel collects any shavings and kills any possible sparks from the drill.
The hole lets you peak down there and verify you are near the fuel sender. It also gives you a place to slide a small metal cutting jig saw blade in to start your cut.
Again keep the towel over the fuel lines and the tank. Carefully cut a window into the floor about 9 inches or so right above the sender.
Pop out the sheet metal from the bed and you have instant access to the fuel pump.
Of course if your like me the sender was also rusted, and had to be special ordered, but hey its easy the second time.
Oh when you are all done I used two small home depot hinges mounted in the valley of the bed to re-install the old sheet metal as a "door" Used a small latch on the other side. If you do it right all the screws on and the hinge are in the valley of the bed. basically they sit below the higher ridges, so you can still slide heave things in with out catching them.
If you ever have problems again its easy to get to, and if you get a tank of bad gas, or some other problem its easy to pump out. never mind the lach of stress from trying to deal with a few hundred pounds of gasoline and getting your hands between the tank and body to tighten the lines up.
Its not a method for everyone, but if your carefull its fairly easy. I think its a lot less dangerous than crawling under the truck trying to fight with a heavy rusted tank and fuel spilling everywhere. Just my opinion.
if there is nothing else please let me know and i will have to burn a saturday dropping the tank and replacing the pump 
....thanks
