Fuel system questions

[speed127]

I am about to install a hahn turbo kit in the comming week and have follwed some of you tips on extras to buy. Besides the basic kit I also have a walbro 255 fuel pump, and a missing link. So hear are the questions... 1 will 450 injectors from a 1g turbo fit if I change the o-rings? 2 I read somewhere on hear (there's so much to read) that if I install a FMU or SFMU that I should take out my stock fuel filter and FPR? Did I just read it wrong? 3 what the dig difference between a FMU and a SFMU? I'm going to get one and some insight would be helpful. 4 Is this the correct way to install a FMU, cause it doesn't really make sense. Walbro 255 fuel pump, to fuel filter, to fuel rail, to FMU, and back to the return to the pump. Thanx everyone for your answers in advance!!!!

 

[speed127]

ANYONE???

 

[ChvyKc]

ANYONE???

I guess that I am a little confused, I don't even know what a SFMU stands for. I know that FMU stands for fuel management unit, so I guess that you are talking about something like a S-AFC. Be a little more specific on what you are asking, in the mean time, here is a write up from RRE on the S-AFC:

RRE S-AFC Tech

But in the way that you are talking about running the fuel system, you ask if you are to run the fuel through the FMU last? Fuel doesn't run through them, I beleive that you are getting abreviations mixed up, I think that you mean to say FPR (fuel pressure regulator) which would be after the fuel rail and yes fuel does run through that and back into the return line. You don't want to take out your fuel filter though, that would be a very bad idea, it ensures that you don't get crap in your fuel rail and in your injectors which would make one or more of your injectors clog. This would could cause you to run lean on one or more cylinders and cause internal engine damage.

Umm, I think that I got all of your questions in that spill, but if not let me know and if I'm wrong about anything, someone please educate me

 

[speed127]

S-FMU stands for super fuel management unit. And fuel doesn't run through them? So basically how do they work? Now I'm totally confused... Where would it go?

 

[ChvyKc]

S-FMU stands for super fuel management unit. And fuel doesn't run through them? So basically how do they work? Now I'm totally confused... Where would it go?

I don't understand why there would be two abbreviations for the same thing. They are both fuel management units WTF I have never heard that abbreviation . Fuel does not run through them. If you were to read the instructions that RRE has on the AFC then that would explain a lot. They basically trick the ECU into thinking that a certain amount of air is running through the MAS to control the injectors and also eliminate fuel cut.

The AFC would sit inside the car and all connections would be made to the wiring harness that goes to the ECU, that is how the AFC makes changes to the way the injectors fire so you can actually tune the car.

Hope this helps

 

[speed127]

ya we are talking about 2 totally different things.... The S-FMU does run fuel through it.. I researched that last night, BUT i still couldn't find anything explaining WHAT it actually does. As far as I can tell it backs up the fuel pressure in the fuel rail. Is this correct? LOOKING for a WISEMAN

 

[ChvyKc]

ya we are talking about 2 totally different things.... The S-FMU does run fuel through it.. I researched that last night, BUT i still couldn't find anything explaining WHAT it actually does. As far as I can tell it backs up the fuel pressure in the fuel rail. Is this correct? LOOKING for a WISEMAN

YOU ARE TALKING ABOUT A FPR, I promise. An FMU does not have fuel running through it. You don't need a wiseman to tell you that, anybody on this board that isn't a rookie should be able to tell you that.

A FPR sits right after the fuel rail and determines the amount of fuel pressure that the injectors see. An FMU and a FPR do two seperate things and you would need both in order to tune your car properly. The following is a link to what Buschur sales as their FPR kit.

https://secure.buschurracing.com/catalog/product_info.php?cPath=22_37&products_id=427&osCsid=b8f6ad87da54d154a1379e8569f1cac1

 

[speed127]

hey thanx for the cool sight...

 

[cs82685]

fmu goes between your stock fpr and the tank, assuming you have the late fuel system the stock fpr will be back near the tank, if not it is near the fuel rail

sfmu, you disable the stock fpr and run a return line from the test port on the fuel rail (late fuel system) to the sfmu and then from the sfmu back to the tank, also you do the same for the cartech fpr,

I assume the same concepts apply for the early fuel system however i have never dealt with it so i cannot be sure