If those new pumps can be dismantled, changing the spring inside will adjust the pressure. The camshaft lobe and the lever that rides on it provide the vacuum that draws the fuel from the tank. The spring and the size of the diaphragm it's moving is what determines the pressure in the line going to the carburetor. Apparently the manufacturers of the new pumps are using too strong a spring in their products. BTW- - - -shortening the length of the spring WILL NOT help- - - - -that actually makes it stronger. A spring with a smaller diameter wire would need to be substituted for the original one.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!