When the fuel tank is just below half full the engine starts to pull air into the system. The fuel gauge is correct. The car runs perfectly until the tank is below half, it then becomes difficult to start. 1996 model.

Peter, it's almost certainly tha fuel pump that under the rear seat. There are 2 chambers to the tank, and the fuel pump balances the fuel between them.
When the pump no longer works, the fuel in the other half of the tank can't be accessed, hence it's really difficult to start, and feel like it has run out of fuel.
It's a 20 min job, and very straightforward.

Stephen

Stephen, thanks for the reply, I have tested for a feed to the pump and that was OK. I assumed the pump was/is working. I will check it out tomorrow. Hope you are right, thanks again. I will let you know.

Stephen, the pump is working fine, it circulates the fuel from one chamber to the other and back again. The delivery to the engine appears to be tee'd off the "pumped" connecting pipe. Any other suggestions, please.

Sorry,Peter, the only thing that I can think of that would cause those symptoms, is the fuel pump ... the "half tank" bit is so specific.

Stephen

Thanks again Stephen, I am going to pick up a manual and check how the fuel delivery system operates. I will let you know of any progress
Peter.

Peter, if you manage to track down a manual, please let me know. I have looked everywhere I could think of, but could never locate one for diesels.

Stephen

hi guys,

i know this post is old but hope for some replies..
i have suffered at the same probelm for about 1 year now, i have to keep the car over about 1/3 full or it becomes difficult to start, it also has cut out on left-hand corners - when the fuel is pushed to the right hand side of the car - and if the car is parked on a slope so the fuel is on the right hand side, it wont start. This problem is hard to rectify as fuel is getting through to the engine, although it has some air bubbles in it. I bought a bmw CD service manual as this is the only info i could find on the car but this doenst help that much. Any further asistance with this annoying problem would be great.

thanks daniel