Not sure disconnecting the battery will do anything, it's always worth a try but since ECU's have been using E2PROMs instead of EPROMs you can't disconnect and dump codes etc, OK it could revert to a base setting but that would be instant as it's only the short term adaptivity that you would be resetting so it happens immediately the feed is removed, the long term is on the E2 and so is electronically erasable and that why you need a code reader to read and clear codes, years ago just pulling the battery until the capacitor discharged would clear all stored codes and put lights out. I am almost convinced Peter will find a previously unknown line fuse behind the dash or somewhere that has blown and is loosing feed to the fuel pump. I had this on an 04 car I was servicing a few years ago.
