Drain back through the fuel pump is a common misconception.  With the needle seat being at the top level of the gasoline within the fuel cavity, it provides a natural ‘air break’ to prevent portiential drain back from occurring.
 
Ethanol laden gasoline does evaporate much more quickly than non-ethanol gasoline so that contributes greatly to the fuel bowls emptying quicker than they use to.  Other contributing factors include leaking power valve gaskets and plugged anti-siphon holes within the carb circuitry.  On the Teapot Holleys’, the anti-siphon holes are located in the fuel bowl cover while on the conventional 1957 and up Holley carbs, those same holes are located in the metering blocks accessed only by disassembling the carbs.  A typical four barrel carburetor can have as many as four anti-siphon holes and any one of these being stopped up can allow a fuel bowl to drain back into the engine.

Lorena, Texas (South of Waco)

I took filter out to see if that was part of problem. The bleed back still happen. I am going to replace pump

When I first got my car it always started with first turn of the key even after sitting for long periods. Now after a week or more I need to prime the carb. My suspicion is the valves in the pump are allowing the fuel to syphon back to the tank. Though I did change from a disposable fuel filter to the original style filter so I wonder if that could have been acting as a check valve.

Today was looking over fuel pump and noticed that what appear to be the pin that must hold the arm to block is out all the way to block. So I am figuring this is not good. Will have to remove pump to check out. The one I had back in high school did not have power steering. Look to be in the way to remove the on bolt. Has anyone done this before. Could give me insite to wether pump needs to be removed or not? Or might it be accessed from bottom?

install a elect fuel pump close to tank,use a cheap low volume top,use a starter button so it only runs when you hold the button. they don't restrict flow when off, plus 1 more check valve. 55 if still 6volt they are avail. did this for several customers.works great for log storage

Most mechanic's vacuum gauges will also measure fuel pump pressure. Maintaining correct fuel height in the carburetor bowl at all times under all conditions is important. Starting with a good fuel pump is key.

Check fuel pump volume as well as pressure. This is a little easier, direct fuel pump output into a container, should fill at least a pint or more in 30 seconds.

I think I might have screwed up. First my photo insert was taken from a band out of Calif. back in 1965 ( Grateful Dead )  The image is called SYF one of many they used.  I hope this did not offend anyone, If so I apologies. I have used this and others on all my cars whether a I inch decal or on front plate. Secondly I noticed that I had time zone from out side US.  I am in the central time zone in southern Minnesota.  You know VIKINGS ( never won super bowl )  But we are all hoping maybe this year, but we have been done this road before so only time will tell. Again hope my profile goofs did not turn anybody off.  Just trying to bring back and expand on my Y-Block knowledge , because I am lucky to now have the car I had in high school when I new it all but with the information I read here I did not know much, but pedal to floor.  Great Forum
  

I have a 1955 ford with 272- 2 barrel carb.. 3 spd. OD.  Looking to how to test fuel pump in place.  Seems to drain most of fuel back down out of filter when park for a few weeks. If i put in line gauge on it would that tell me anything that would help?  What would be best way to test the pump?