Every time my 1996 2.8 A4 B5 sits overnight, it looses residual pressure. First Audi but have replace VW check valves on fuel pumps before. Has anyone else experienced this? Replaced control pressure reg and vacuum line to it. Once warmed, will start the rest of the day. Cycle fuel pump in morning about 20 times, and it will start rough but clear out. No CEL. WTF?

 

Maybe the pump is going bad. Even if you lost residual pressure, the pump should pressurize the line as soon as the key is turned to the run position. Can you hear the pump when you first turn the key to the run position? Have someone stand by the rear wheels and listen for the pump, or put their ear to the rear seat to listen for the pump. There have been a few post I have seen where people are having the same cold starting issues on their V6's. Constant cranking and cycling the key on and off to get fuel pressure, has been the theme of those threads. I haven't seen a solution, Try a search.

 

Your fuel pump is most likely bad. I can hear my lines pressurize from the drivers seat when I turn the key to the "on" position. I haven't had fuel pump problems but my dad's chevy truck did. He'd loose residual pressure in the lines and he let it go 'till one day my mom was driving it and it didn't start at all. Take it to your mechanic and pay the 50 bucks or whatever he charges to have him check it out. Bottom line: nip it in the bud now before you have to have it towed later.