A while back when I was looking at fuel pumps online, I noticed that some of them had a warranty that was only good if you replaced the mesh filter at the same time as the pump. Are you saying that you did replace the whole pump/mesh filter assembly with an aftermarket and the aftermarket mesh filter caused the problem? Was it your old stock filter screen that you put back on?

Turns out my problem was the main relay, not the filter pump so I re-soldered that and so far, so good. However, it would be good to know whether to avoid afermarket fuel pump fliter assemblies if that is what caused the problem.