2018 GT350 using a return fuel system.

[bbrooks98]

2018 GT350 using a return sytle fuel system. Typically we set all the fuel rail pressure values to 55 on the coyotes for the two tables, but there is an adder table that is additional on the GT350s. What is typically done with that?

[bbrooks98]

2018 GT350 using a return sytle fuel system. Typically we set all the fuel rail pressure values to 55 on the coyotes for the two tables, but there is an adder table that is additional on the GT350s. What is typically done with that?

I should add zeroing it out isn't really an option as the min value is 30 without overriding default values.

[decipha]

they already come stock with a return style system the regulator is just installed in the fuel tank to make the return line shorter

there is no delta pressure compensation, dont even have a fuel rail pressure sensor

no changes are required moving the regulator from the tank elsewhere

[murfie]

If anything, having the regulator at the fuel rail, would negate the need for temperature compensation, so if you are using 55psi(delta pressure) across the board, then 70 psi(absolute) across the board would work. Set the base pressure after everything warms up with hood closed, then tune.

[bbrooks98]

If anything, having the regulator at the fuel rail, would negate the need for temperature compensation, so if you are using 55psi(delta pressure) across the board, then 70 psi(absolute) across the board would work. Set the base pressure after everything warms up with hood closed, then tune.

This is what I have it currently set to which sounds like it should work. Its a newly installed twin turbo kit. All the codes fuel pump related that popped up were set to no error reported. What I've got is the fuel trims are way lean (60+ STFT) around 3k and up just free revving. I've taken the car back to almost stock trying to rule things out. Stock injectors, stock throttebody, stock intake and IMRC settings, stock torque values etc. I trimmed the maf for the 3inch pipe with basically an across the board multiplier used till the fuel trim was close to zero around idle.

This car is a buddies car i'm helping remotely so the probability of other mechanical issues i can't see is definitely a factor. They claim pressure is holding 40ish in vacuum when this happens.

[murfie]

If they have the 1:1 referencing the MAP it sounds about 15-20psi low, can't have a 55psi delta with only 40psi in the rail.

[bbrooks98]

I assumed the vacuum at part throttle it would be referencing the regulator to a lower pressure than 55psi. It was set to 55 at idle with the vac line removed.

[murfie]

55psi with vac line removed, referencing barometric pressure, gives you ~40psi delta. Needed to be 70psi for a constant 55psi delta.

Delta pressure.PNG

[bbrooks98]

That makes sense with the logic and their absolute value of 70. 70 psi rail pressure in my head should be roughly 15psi worth of boost and a 55psi delta between the injector tip and the fuel rail.

[murfie]

I think you are use to coyotes and their 55PSI(58Psi) absolute rail pressure.

[bbrooks98]

I think you are use to coyotes and their 55PSI(58Psi) absolute rail pressure.

This is definitely true! Just so i'm on the same page. So given that I should set the absolute pressure to 55 and and the delta to around 40 from what it sounds.

[murfie]

High pressure makes the injectors work less, you can get away with small ones, and keep great idle and drivability, OEMs are doing it to remain emissions/ fuel mileage compliant. BUT you need a beefier fuel system to keep up and withstand the higher pressure.

[bbrooks98]

I did not realize they were that high now (70psi base). That and the description of "adder" got me. Thanks!

[bbrooks98]

UPDATE: Finally went in person to look at the car cause nothing seemed to fix the trims. Turns out it had a plastic wrapper in the charge pipe wrapped around the maf.



Runs smooth now and trims within 3%

[AdmiralSparklez]

they already come stock with a return style system the regulator is just installed in the fuel tank to make the return line shorter

there is no delta pressure compensation, dont even have a fuel rail pressure sensor

no changes are required moving the regulator from the tank elsewhere

Considering this thread is 4 years old I'm sure you know by now, but just for all future viewers of this thread: No, the GT350 and GT are not return style systems from the factory whatsoever. There is no return line to send excess fuel back to the tank. And the GT350 does have a fuel pressure sensor mounted to the rail, which sends PWM signal to both FPDM (driver module), along with two fuel pumps in the pump basket. The GT only has one fuel pump in the basket and one FPDM as well as no fuel pressure sensor (more so speaking of the Gen 2 as it's similar to the Voodoo).