[luckyed7711]

"My results so far: Fuel pressure at the rail after the fuel pump runs for a few seconds with the engine off is 50 psi. When the pump's no longer running the pressure starts to slowly, but steadily bleed off, until a day or two later there's no pressure at the rail.

Start up the car, engine at idle, the fuel pressure is steady at 57-58 psi, and as I said the car runs fine until it stutters and/or stops.

I believe the fact that the pressure is higher with the engine running than when it's not running is the opposite of what is supposed to happen, no?

Can anyone suggest what my results indicate? Could the fuel be bleeding back into the tank and suggest an issue with the regulator?"

Further results: So I checked the volume/flow rate by removing the fuel line at the top of the tank, attaching a length of hose to the nipple and running the fuel pump for 30 seconds into a container. This is another test that the Bentley manual claims, in error, cannot be made for 2002-2004 systems without a diagnostic tool. (note to future DIYers)

In 30 seconds the pump put out about 1.2 litres, well over the 850ml minimum given as passable. Unfortunately when I reconnected the fuel line it now leaks at the connection. I'm hoping there's an O ring in there that I can replace. Anyone know?

However, although the fuel pressure while running seems to be in spec, and the flow rate seems to be more than adequate, I've still got pressure lower while not running than running, instead of the other way around. Also, after checking the volume, I was able to, fairly easily, blow the fuel in my test line back into the tank the wrong way through the pump.

Should that be possible? Can this mean a faulty regulator? If the regulator is failing and my pump runs fine I presume that I'd have to by a new fuel pump ass'y. anyway as the 2 components are apparently integrated?