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Jim Adney wrote: >Here's my guess: After you shut down a hot engine, the heat causes >the air in the lines to boil and that pushes the liquid fuel up into >the tank. Once things start to cool back down the various check >valves prevent fuel from flowing freely back into the lines as the >gas fumes condense, so a (slight?) vacuum is created in the lines. >This vacuum is sufficient to pull air into the lines thru every >available leak so the lines are empty the next time you try to start. > > > That makes a lot of sense- one thing, though. The car was running maybe 15 minutes before I put it on the flatbed, and it was fairly chilly. I guess the engine compartment need not be too hot for the fuel to begin boiling- one quick check on the MSDS for a leading manufacturer's regular unleaded states the boiling point is 77 deg F. Engine compartment can easily reach this temp in a few minutes even on a cold day. Now, per Russ' note, a 3cc/min air leak at 70PSI is considered accetable to not leak fuel. Could the injectors leak this much air, even new? Couple of other thoughts: The pressure regulator is designed to shut if pressure drops beneath the set pressure, and this is a pretty bulletproof device. So, with the pump not delivering fuel, it can be assumed that this valve stays shut. The only way for fuel to then get sent back into the tank is via the pump. The pressure relief valve is also a check valve- therefore, fuel has no way to get back to the tank unless the check valve piston no longer seals, or somehow the pressure of the lines exceeds 64 psi (the pressure at which the pressure relief valve discharges to the return.) Jim's experience with the new check valve piston would seem to confirm this. Perhaps it's no accident that this function was designed into the pump. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~