Turns out that air is making its way into the fuel line slowly and accumulates as the car sits. Hooked up a gauge to test Fuel pressure and used clear tubing between the gauge and the filter. Based on the gauge the fuel pressure hits 42-44 psi during the 2sec prime and about 48psi while cranking. About 34psi while idle and then 42psi with the vacuum line going to the fpr unplugged. I think the gauge is just off by about 2psi which is why it isn't exact to the fsm specs. The pressure took a few hours to bleed off to zero (at least 2). The next morning, which would have been Friday past, I found the air bubble in the line. By Tuesday the section of clear tubing was completely filled with air. About 1ft length of tubing. I'm sure the air is coming from the supply end and there is probably more between the tank and the engine bay.
I don't smell anything to indicate a leaky hose outside the tank. I was thinking to change the section of hose between the tank and the hardline as well as the in-tank hose on the pump assembly just to be sure they aren't leaking. But I also read of a check valve that's part of the pump itself that can cause this. Any thoughts? And is there a clear indication for an OEM pump as well as NA vs TT for inspection purposes? Thanks
"torque gets you off the line...& hp gets you over the line." - TTKeeper
Follow Ups
Slow fuel drain-back as car sits=air in fuel line. Thoughts? - LivinTheDream13:22:37 10/16/14
