M5 Guru (>2000 posts)
Join Date: Nov 2010
Location: Sanborn, NY
Thanked 289 Times in 249 Posts
To answer your question directly first, there is no PM you can do for the pump. People will say don't run the tank down to low but I've never subscribed to that theory and I got more than 130k out of a replacement pump before it went.
For your situation, you should probably start thinking about replacing the pump. 100-130k miles is pretty typical lifespan. The relay may have gone bad because the pump is making it work harder all the time... gets hot and eventually died.
You could be weird like me and just keep a pump and a few tools in the trunk to change the pump where ever it dies... including on the side of I-90! If you've "been in there" before then you really don't need much... flatblade screwdriver, a hammer or in my case a small block of wood I keep to use with the scissor jack, and a razor blade from your temporary flat repair kit if you keep one. In order for this to work you need to just replace the pump itself. I've been running a Walbro. You have to change the connectors but once done, it's plug and play for another Walbro or the factory Pierburg.
2013 M5 Imperial Blue/Silverstone II, 6MT 64k miles
2000 Anthracite daily driver
UUC dssr and shifter
Supersprint headers with Tubi catback
Dinan 3.45 JED lightened flywheel
286,000 miles and counting
'00 Imola/Imola 107k stock
'00 Silverstone/Silverstone 129k (SOLD)