Between 20 some year old connectors with maybe seals that are no longer that great and maybe the mating surface on the pump side isn't perfect, I would at least definitely use some contact grease. It seems to be a known issue even from the factory and sooner with the E70 so I went with wiring everything direct on the E53, you need to make sure you get a good seal on the wires though or you'll get a CEL for tank leakage! Tank leakage code might also be a hint to maybe having a melting connector issue!
