No fuel return line (fuel upgrade)

[Spyke169]

Not sure if it has ever been done on a dsm but the infinity g35 has not fuel return line. There is a fpr in the fuel feed line to control the amount of fuel going to the injectors. The fuel then does not get heated up and then sent back to the tank. Thus cooler fuel is more dense fuel. Alot of maxima guys that swap to the vq35 from the vq30 do this. There are probably more high points to this than what I know but I can't search the maxima forums and look.

 

[Jazzie6044]

the first thing that comes to my mind for trying this is how do you control the pressure? running a vacuum line that far would not work well, so some alternative would probably be necessary.

 

[dave99gst]

its been done --
also using 2 f/p's ( one of each side of the rail ) has been done as well.

 

[99gst_racer]

Yeah, the Neon SRT4's have a return-less fuel system too. Do you know approx where they have the regulators at? Is it in the middle, or closer to the tank or motor?

I have many of my hot rodder customers convert their old SBC's and BBC's from carburated to EFI and they always run a return line to the tank. I forgot why they do it. One of them explained it to me once; something to do with maintaining fuel pressure and fuel in the line upon starts. They swear by the return system.....

 

[Winall]

Their are three (efi) systems;

•Mechanical return (our cars)
•Mechanical return less (str-4), the fpr regulator is in the gas tank.
•Electrical return less (some of the newer GM products) has no fpr, the pcm uses pulse with modulation to control the fuel pressure

Their is a lot more to it but this gives you a rough idea, both have good things about them.
Mechinical return is always filtering the fuel. Electrical has no extra lines of a fpr, ecu controls every thing.