Bizzare washer pump behaviour

[audiophool]

2004 X5 3.0i FWIW.

Windshield washer pump works for a while then won't pump. Pump runs normally but doesn't pump. Rear washer pump runs and pumps at these times.

Today, I pulled off the wires and swapped from the pumps and swapped them. Then the front washer worked and the rear didn't. Odd thing is both pumps are new, replaced by the PO when he was trying to solve this problem.

I pulled the pumps out and noticed there was a vacuum when the first pump came out of the reservoir. This would indicate the pump is trying to draw against a vacuum and cannot.

Poked a hole in the tank lid and cleaned the intake screens. We'll see if that makes any difference.