Attached is a Diagram of A Return-less Fuel System with Vortech FMU and Inline pump. Diagram from Vortech manual.

I would like to know if anyone can explain how it works? I have this setup in my can and know that it works.....

The Funny thing is that when I talked to Vortech about there FMU, they said "FMU'S are meant to be used on Return style systems not a Return-less style system" per Carlos Lopez.......

 

Kinda looks like a basic rising rate fuel pressure regulator.

As vacuum decreases (or positive pressure increases in FI cases), fuel pressure is increased (to help flow more).

 

It's just overpressuring the fuel system, and returning nothing. It's a cheap and simple, and allows them to retain the OEM injectors. Not the textbook way to do it at all. That's why we always suggest the tuner kits, without their included fuel and engine management.

 

Thank you for you comments....

I know what it does. Yes, it's a rising rate FPR.

But, how does it do what it does?

 

Its all based on manifold pressure/vacuum.

The pump is running at max potential all the time, but the fmu holds back a certain amount of fuel pressure based on the manifold pressure.
As the manifold pressure goes up, it opens the fmu allowing more pressure and flow from the pump (up to the pumps maximum flow rate potentially)......

The problem with these styles is, what happens when you let off the gas.....The pressure needs to go somewhere......

Tom

 

Tom,

I had it backwards, I thought it closed with boost, and could not see how that would work....

Dyslexia got me again....

Thanks
Tim

 

Often overlooked is the fact a return system lets front and rear injectors flow more evenly. Without a fuel return, the rear injectors get more pressure than the front under heavy load.