1150 gs fuel pump
 

helo to all from austrailia I have just bought myself a 2000. 1150gs but having starting problem

the fuel pump is a bit noisey so I think it may be the cause but how ever I thought I would ask. it starts cold some times and if it does not keep running it will not start for half an hour or so and other time it will not start and run down the battery. when I do manage to get it going and it is warmed up there is no problem. is it possible that there is a fuel pressure gap between running pressure and pump starting pressure that turns off the fuel injectors but not low enough to restart the pump.:

The pump (nor anything else other than a simple mechanical fuel pressure regulator) ) does not sense fuel pressure.
If you have a CANBUSS controller then it simply turns the pump on and off rapidly to reduce the pump output from maximum (thus reducing the heat put into the fuel). The CANBUSS tells the controller the engine speed and fuel requirements from the EFI information and that sets the controller electrical output to the pump. You can short out the pump supply to make the pump run flat out (like it used to in the pre CANBUSS days).
There used to be a simple fuel filter that you could change. The filter would absorb water and swell up eventually blocking the fuel supply. Check you don't have one installed by a previous owner.

The fuel pressure should be constant .. hot or cold .. about 35psi IIRC.

The 1150 doesn't have a CAN-BUS system. A fuel filter failure is certainly a possibility. If you're not sure of the service history it's worth replacing it.

Spurious fuel pumps are available online, much cheaper than OEM.
When the problem occurs you could remove an injector and see if fuel is delivered.

A 2000 model is a single spark. It doesn't sound like a plug coil failure and, anyway that's more common with the later twin spark model.

On an 1150 that age it's important to check the brake hoses. Have they been changed - for stainless braided hopefully?

PS You might get more responses posting in the BMW forum.

No CANBUSS = simpler ..
Check/change the fuel filter. That way you know it is done.
Disconnect the pump, reconnect it directly to the battery ... but with the terminals reversed - + to -, - to + ... this makes the pump run backwards .. any dirt in it should come out.

When the fault happens ... is the pump running/making noise/pumping fuel around? .. you should be able to see the returning fuel to the tank making a flow.