Hi,
I was reading through some older posts and read your fuel pump question. The original Sunbeam mechanical fuel pumps have a prime lever on the bottomside of the pump. When I’ve left my cars sit for a period of time and I don’t want to run down the battery I will pop the hood and manipulate the prime lever. You can hear the gas entering the fuel bowls and also hear when it stops filling the bowl. This may help with starting after the car has been sitting. (Replacement pumps may not have the primer lever.)
Gasket thickness between the pump and block will also affect the pump pressure.
I’ve found the mechanical pumps reliable and have driven my Alpine across the country twice as well as taken many other long trips.
A bigger fuel supply problem I’ve had is from paint which flakes off the interior walls of the fuel tanks. This can clog the fuel line at the center of the crossover tube between the two tanks where the fuel line connects. I have also had it mess with the fuel pump. For a while I kept an openable fuel filter in front of the pump and would remove flakes of paint as big as my thumbnail. Under heavy acceleration they would get sucked against the tube inlet and start to stall the car. Eventually to solve this I pulled the tanks and had them boiled out and coated. Anyway paint flake clogging can really cause fuel supply problems.
Dave Reina
66 Alpine