If you read thru some of my lengthy comments on this thread I mention Marine accl pumps being different than automotive.
VERY IMPORTANT to use the correct pumps in them so there is some pump shot left to prevent stumble/hesitation/bog when already up on a plane and moving the Morse controls ahead to speed up the boat.
If you use a automotive pump there is no pump shot left in that scenario. The factory knew this, or at least figured it out and used very short pumps in Marine units.
With that said every single troubled Marine Q-jet sent here for me to rebuild it again has the WRONG pump in it. They are also putting the wrong duration spring on them (in some kits where you get the complete assembly), too long and too many coils so they "stack" when compressed.
The light blue "soft" seal isn't worth two squirts of duck poop either, and the black ones are even worse, but I like the fact that they sell them and folks think they are good to go installing them. Some weeks I sell so many pumps I can hardly get anything else done!............Cliff