The return regulators near the tank with a deadhead line to the engine compartment are nice, but it is still much better to use PWM to control and match the power to the pump to engine demand in any of these systems.
Wondering if this variable pump output is a fairly new development, or has automotive been doing this for some time? If so, do all cars use this type of fuel pump system, or limited to high end and/or expensive cars? [/quote]
The concept has been around for decades, but actual PWM in production cars seems to be a relatively recent development. There's not much history about it found in a surface search of the web.
Most modern production vehicles use PWM to control the fuel pumps for several reasons including increasing pump life and reducing the heating effect in the fuel tank especially at low volumes. Most factory in-tank EFI pumps are pretty quiet by design and placement. Even smaller displacement low-end cars use this technology, but it is the high flow, high output systems that really benefit from the technology.
