OK,Here is my problem. This started months ago out of nowhere. I went to start the car and noticed the fump was not pumping. After removing the line and blowing thru it the fuel began to flow. I figured I had garbage in the tank so
I found a new tank with a good screen and replaced it along with a new rotary pump which I mounted under the tank. I also blew out the lines and removed the carbs and cleaned the jets. I tested it today and after about 5 miles the motor started to buck like it was not getting fuel. I got it home and when I looked at the fuel pressure gauge it was reading 0. It seemed like the pump just quit pumping.
After letting the car sit for about an hour I turned the key and the pump was pumping at about 2 or 2 1/2 psi. Is this a pump problem, electrical problem or
what. The tank is full, the timing is perfect, the carbs are clean. The motor is a
2 liter with weber 40 carbs. I have a filter at the pump and a filter before the
Holley regulator.HELP

is the pump running? what is its power source ? are you sure you plumbed the input to the pump from the tank delivery port and not the return port ?

are any of the lines to the pump or on the delivery side from the pump to the carbs kinked or pinched by the tank (real common ...) ? do any of the fuel lines run too close to the heat exchangers / headers ? (could be vapor lock...)

"seemed like the pump quit pumping" -- did it, or not?
if you suspect the pump (what kind is it?) you could temporarily replace it with a Facet to try to isolate the cause.

Make sure the pump has a reliable (ie clean and tight) electrical ground to the chassis, especially if your car is a '75 or '76.

I had a Facet pump before I changed it. Like I said everything was perfect then out of nowhere this problem starts. I checked all the lines and no kinks.
As far as heat, there are no lines near the headers. When I installed the new pump I also installed a relay so I would get good power. I will check the ground
and also make sure I have power when it stops pumping. It seems like the pump
is starving for gas from the tank.Maybe I need a higher psi pump then just adjust
it at the regulator. My car is a 71. This is driving me crazy

Check your Fuse relays also!! I had a problem where my relay board kept shorting out the Fuel Pump relay, it would work sometimes and then other times it would not, move the relays around and see if it starts OK. I eventually swapped out the relay board and the problem went away.

Lou Smaldino

If you can start, run a few miles, then have problems with starvation, it sounds like the tank vent is blocked. After you wait awhile, enough air bleeds past the block to allow you to start and run again until you get sufficient vacuum above the fuel that the pump can no longer draw fuel from the tank. Pop the gas cap when is starts bucking and see if that fixes it.