[Pman1961]

I've been googling and reading up on the advantages of a return line system, hp pumps with external regulators. It seems as though the pumps are running full speed and when there is less demand of fuel it creates a deadhead situation, cavitation, more heat, reduced life of pump. With a return line system the excess fuel gets pumped back into the tank. My question is and I must admit I have not researched as I'm working on the car and am hoping for an answer this evening checking on comments. Do internally regulated pumps go one speed and one speed only if it states maximum pressure of 7psi? I know when you turn the ignition on you can hear the pump change tones when the fuel system is fully primed so I would assume it runs full speed at all times. Yet what is happening to the fuel in the pump if not needed at the motor? Is the pump chopping away at the fuel in the pump or is something else going on that I'm not aware of? Again, I need to do a little more reading but does the return line need to come off the regulator or can it be elsewhere on the fuel system or do some pumps have a return line output? Again, apologize for not doing my home work. Just a lot going on and looking for people that have been there and done that to respond. Thanks.