PWM'ing is also useful with pumps like the Bosch 044 as it allow a stock type fuel pressure regulator to regulate the pressure even at low loads. It's common to see that the fuel pressure increase a bit at idle because the regulator can't deal with the flow. We try to keep the stock type regulators as long as possible as most aftermarket regulators have serious problems. -Jörgen

But trying to regulate the pressure of the fuelpump is technology for technologys sake which is always bad. An open loop table where the the PWM percentage is mapped over load and rpm is what the above car applications need. You basically let the pump run at half speed when idling and when driving at low load/rpm but over a certain threshold in the table you disable the PWM and let it go at full speed. Extras: Controlling a relay that bypass the fuelpump PWM when it's at 100% to avoid having all that current flow through the FETs. We also need a settable fallback lag that allow the pump to continue at full power during shifts and when feathering the throttle. - Jörgen

The fuelpump manufacturers own applications for slowing down the pump at low load use a proper regulated and smoothed switched powersupply. I can only draw the conclusion that the pumps don't like to be PWM'ed from this fact. So at the very least we need a small box with an inductor and a big capacitor for the directly switched applications. For the larger pumps we need external switch hardware as well, but that is easy to implement if the pulsetrain itself is available from the ECU. This could be built with boost capability itself which would make it viable as a standalone product. -Jörgen