If you are talking about the fuel strainer under the tank then all you really need is a pair of pliers. This is not in there that tight as it is too flimsy to take a lot of torque.

For something like this I would start at the strainer in the tank and move towards the carbs, cleaning not only the strainer but also running a brush through the steel gas line along the bottom of the car.

I usually run a piece of steel cable through the line since it will go all the way through. Then I tie a piece of fishing line to the cable and pul it through. Then tie a pistol bore cleaning brush of the correct size to the fishing line and pull it though.

Then at least you are clean up to the fuel pump.

But I think the trouble is in your fuel pump. As in a check valve has failed due to a piece of dirt in it. These mechanical pumps are not expensive and are also not hard to install. At one time you could buy a rebuild kit for them and that's pretty simple, too.