I had this. Hope you have it sorted by now, but if not, I didn't remove the bumper to change my pump. I just undid a bit of the arch liner, pulled it back a bit, and had enough access to the water bottle / pump, I was able to swap it out no problem. Just make sure you have a bucket or something to catch all the screenwash.
Not sure if that was actually the issue though, as when I had it out, I tested it, and it worked ok. Swapped pump anyway, and then it didn't work again. Have to investigate further. Intermittent problem though. So gonna try blowing back down the jets later, see if it cleans something out.