69 CST10 fuel pump to carb problem

[kbill45@gmail.com]

69 with 350 and auto trans. The engine is 350 supposedly out of 75 Camaro.
600cfm(1406) Edelbrock carb and intake, new fuel pump.

Problem Cranks right up cold but takes the battery way down to crank when hot say 10 minutes later. Put a clear fuel filter on to check what was happening. When the engine is turned off gas keeps flowing in until filter is full. Clamped off the rubber line immediately after shut off and
release it after 10 minutes and it starts right up. Was doing this with the old pump also. Took the truck to a repair shop and it baffles them too.

Any ideas. I am about ready to install an electric with an on off switch like I used to run when I had mirror finish cylinders and double moly rings 40 years ago.