how can I fix my E46 330D "no start"?

Year of mfg 2003. The car has always run very well. Last week on 2 occasions it was very difficult to start though worked well once running. Since then whilst the engine turns over it won't even try to start. I noticed there is a hissing bubbling noise coming from the fuel tank when the pump is powered up, I removed the hose from this pump outlet and connected a seperate tube, when the pump is powered fuel flows from this tube so the pump seems to be working okay. Could it be the pre-pump that is fed from this (tank) pump that is not working? could the unusual noise coming from the tank be a pressure overflow on the tank pump? I really do need to use the car but right now don't want to pay BMW towing and repair costs. Any useful suggestions or comments would be appreciated.