fuel pump secondary circuit??

Ive got 4 codes on my 99 Passat 1.8 as follows:

P1237 Fule pump secondary circuit malfunction OR vacuum switching valve 2 circuit malfunction

P1238 Vacuum switching valve 3 circuit malfunction

P1239 Manufaturer specific powertrain touble code

P1240 sensor power supply malfunction

Seems to me that they are all related since the codes are in sequence and seem to be related to the fuel system. hopfully one fix will cure them all but im not sure where to start. Anyone have any suggestions or more info that might help??? It would be much appreciated!!!!

Is you battery voltage low?

battery voltage should be ok. Its a fairly new battery and it sounds fine starting. Ill give it a test to make sure though.