The pick up screen is at the bottom of the pick up tube, the pick up tube is attached to the gas tank. Ity is where the fuel line connects........
IF it is this, then the pickup tube must be removed and checked or repaired......it also could be something in the tank other than the screen..
what can be done is to remove the sending unit from the tank, where the wires connect, and look inside the tank and see what you can see.
DO NO USE ANY FLAME DEVICES or AC POWERED LIGHTING TO LOOK INOT THE TANK, USE A FLASH LIGHT!!!! LED IS BEST!!!!
Many who look use a lighter to see............so guess what???? BOOOOOOOM!
Also make sure the vent line is clear. You should be able to blow air into it from the outside into the tank. Use air only.........