[D-CEL]

It doesn't make sense to me that you have that much pressure building up in the fuel tank.
1) Is it a return or dead head type fuel system?
2) Do you have a fuel pressure gage plumbed in ? Id be curious to see what it reads when you first start the car VS. after it has had time to build up pressure.
3) Have you tried leaving the cap off (closing the quick fill?) and seeing if the condition persists?
4) What type of ignition do you run?
Id put my money on carb adjustment.

JASON