A little over four years ago I did the fuel filter “upgrade” on my 1.9L
Westfalia. The small filter on the intake side of the pump was removed and
a larger fuel filter was put on the output side.

About four months later I pulled out of a gas station and jolted the van in
a dip at the curb that I didn't notice. The engine died and wouldn't start.
I had no idea where to start troubleshooting so had it towed to the VW
dealership, where they replaced the fuel pump. Everything was fine until
our first trip after the repair. The fuel pump started buzzing. We made it
back OK and after researching Samba and other sites I determined that the
gas tank was rusted and particles were clogging the fuel pump. Sure enough,
when I removed the fuel pump and tapped the pump on a 2 X 4, particles of
rust dislodged from the intake screen and fell out. I replaced the fuel
tank and put the small intake filter back while keeping the larger outlet
side filter. It still buzzed some but didn't get worse. I assumed that
there were some particles trapped in the screen that wouldn't come out.

Last week while returning from a trip the pump really got loud. It even
seemed like it was harder to get up hills. I'm replacing the pump but I
wonder: by having two filters did I put too much strain on the pump and
caused premature failure or is there something else I need to look at the
prevent premature failure of the fuel pump?