The pressure a pump produces depends on the strength of the return spring. The cam lobe simply creates the suction to pull the gas from the tank to the pump- - - -the tension of the spring determines the fuel pressure the carburetor sees. Those super-stiff springs some manufacturers use will overpower the needle valve in the carburetor by developing 10 PSI or more of fuel pressure, instead ot the 2-5 PSI the carb is desined to get. That's why doing a pressure and vacuum test on the newly installed pump isn't just a good idea- - - -it's something I do just about all the time!
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!