For anyone who still has the BMW D7 installed, I recently had a problem with the fuel lift pump. The engine would start and idle without a problem, but as soon as more fuel was demanded, it would falter and sometimes stop altogether.
When I had dismantled the pump, I found the diaphragm was intact but the holes for the fastening bolts had elongated and were allowing air to enter.
The diaphragm is not replaceable, so I was faced with purchasing a new pump for £150.
I cured this problem by making a gasket from a glossy magazine page and placing it on top of the diaphragm, to make a new seal.
This remedy was somewhat cheaper than replacing the pump, which someone might do, if the exact problem wasn’t identified.