Strange non-return valve on fuel line.

[Vanordinaire]

The initial message was deleted from this topic on 12 July 2019 at 22:43

[GreenV8S]

Presumably there was supposed to be a diaphragm and spring in there. Since there are no remains at all in there I guess it was an assembly fault. Maybe the fault is becoming apparent now because the pump is worn and leaking more?

[E-bmw]

Makes sense, a pump will normally "hold back" the fuel as well as the one way valve but as pumps wear their seal gets worse.

Either way, well done with your fix & FYI the reason it would start better after turning it on for a few seconds first is that the pump starts up immediately to ensure there is fuel pressure for start up.