1960 Gas Check Valve

[60eldo]

After shutting my car off, maybe in 5 minutes, the gas from fuel pump back,seems to drain back to the tank. Is that normal. Wondering if theres a check valve somewhere thats not working.

[TJ Hopland]

The fuel pump has check valves in it, not to prevent drain back specifically just to make it function.   When the pump diaphragm is moving up the inlet check valve is shut so the only place the fuel can go is out the outlet so its valve gets pushed open.  When the diaphragm is moving down the outlet valve shuts so it can't pull fuel out if the carb so the only option is for the inlet to open so it can suck from the tank. 

Those valves usually have springs but they are not especially strong since they are working under pressure.  Sometimes there are no springs just gravity and pressure.  Depending on the model the seats/seals are not that precise either so what could be happening is without the pressure of the pump operating there isn't that much seat pressure so fuel can get past em especially maybe with a little heat soak raising the pressure. 

I think from a design standpoint they were not that concerned since the carb bowl should have enough fuel to get the engine started again and run long enough for the pump to get things moving again.  You may have a combination of modern fuels, heat, and a little wear adding up to cause what I assume are long crank times.   

[Jeff Rosansky CLC #28373]

I'm wondering about your tank vent. If there is a vacuum there, it would activity suck fuel back. Next time you drive it, take the cap off when you shut down, or just before. Worth a try for troubleshooting purposes.