Ok so i had problems with the original fuel pump with just no fuel gauge working at all. Ordered and replaced the fuel pump with a new one from lucky 8. Now my gauge works but when I get down to about a 1/4 tank full it surges when you apply the gas to it. Once at speed it smooths out but till then hold on. Refueling the tank problem goes away. Last fuel up added 19 gallons to top it off. Problem goes away till you get to the 1/4 tank mark. I am at a loss here?

 

This situation just happened with my wife's Volvo XC90. Based on what you are saying, I think your replacement fuel pump is defective. I replaced hers because it was doing exactly what you said once it got to 1/4 of a tank. The repair shop gave me the choice of replacing the pump or never letting the tank go below 1/4. It was explained to me that part of the job of the fuel pump is to transfer fuel between the baffle that separates the right and left side of the tank itself.
FWIW.