Put a pan under the tank and unhook the line coming from the tank to the pump. If fuel poors out its not the tank screen. If it doesn't poor out put a hose on the pump and run it into the can. If the car starts you know your pump is good and the tank is plugged.

__________________
81 300SD daily driver/project
86 420SEL (sold)
85 380SE(in the graveyard)