Non return valve needs replacing

Hi,
I went fishing a week ago and my car just would not start it had to be towed home. The problem is that it will start one minute and next minute it wont start unless I fill the fuel filter with diesel.

Had codes read and one time the mechanic said it was showing as non return valve needs replacing and today had them read again and showing these codes :

1260 delivery pump control system
0404 Exhaust gas
1612 Engine control module incorrectly coded
11?0 ( BAD WRITING BUT KNOW ITS FOR REGULATOR )
1255 Deliver pump pressure sensor
1195 Fuel pressure control sensor / valve

Also started smoking a bi, has little loss of power and fuel runs bank into the tank when I turn off ignition which empty's the fuel filter.

The mechanic thinks its something to do with a little pump that is behind the back wheel.

If someone has any idea what needs to be done I would massively appreciate it as I have not been able to work as car keeps letting me down when going on jobs etc and mechanics in my area seem to be useless.