So i have a 87 s4 n/a fc, just out in a welded diff and it was fine, while i was drifting it would randomly just cut out sometimes and didnt worry about to it much. Then i was going to a car meet and was driving on the highway and randomly just died, rpms were still going but it was getting no fuel, so i got the injectors serviced and changed out the fuel filter which i thought was the problem cause it seemed restrictive but it wasnt and i tested a lot of things out. AFM, taking off the fuel line to see if fuel was getting to the fuel rail, jumped the yellow two pin connector to make sure the fuel pump was on, thought i might be the main relay so i took it out and jumped that still no fix. made sure the injectors clicked by taking out the CAS and spinning it. i am so lost at this point it seems like electrical but idk anything i tried looking at all the fuel forums and nothing helped so im hoping by the end of this thread that ill have my car running and ill learn something from it.

 

try removing the harness at the pump and testing the "car" side of it. if that passes (which it probably will since you said the relay tested good), then test the pump itself.

when you remove the pump, also check the inlet filter as well.