Yeah, the check valve is what the accumulator maintains fuel pressure against. If you've got a failing check valve, symptoms will be indistinguishable from a failing accumulator. You can and should test the fuel pressure leak down after fuel pump shutoff with a fuel pressure test gauge. Fast residual pressure drop is a problem.

I found this nugget on Pelicanparts.com:

My 911 won't start after sitting when it's warm. What could be the problem?
When I first got my SC, it was very difficult to restart after it sat for 30 minutes or so. Turned out it was the fuel accumulator, which holds system pressure after the engine has been started. You can check this out with a CIS pressure gauge.

This problem can also be caused by a defective fuel pump check valve.Even if you have the pump with the integral check valve, and it is defective, you don’t have to replace the whole pump—just add a separate check valve in front of the defective one. The separate check valve is a Porsche part. For the 80-83, the part number is 893 906 093 (M12x1.5--M12x1.5). For the 84-89, it is 944 608 951 00) M10x1.0--M12x1.5). About $15 from Stoddard, 800-342-1414, or your local dealer.

Bob Tindel
btindel@gte.net

Brett