WARNING! FMU placement

[Kooldino]

Ok, it's come up in other threads...the FMU placement. Terry's install manual says...

The FMU splices into the factory fuel line before it goes into the oem fuel rail. The top nipple connects to a vacuum line that will provide boost to the unit allowing it to increase fuel pressure when needed. The factory fuel line will need to be cut (fuel line coming from gas tank) this will be inserted in the intake of the FMU located under the unit. Then the outlet will be connected to the fuel rail this will be shown in greater detail in the following pictures.

As stated in other threads, it makes sense to put it AFTER the fuel rail and stock FPR so that it restricts fuel RETURN thus rising pressure in the line.

Being that the spool manual is a bit confusing on this (to me it seems like it's saying to install it after the fuel pump, but before the fuel rail), I suspect some people installed it before the fuel rail...and if so, they aren't raising pressure under boost. Anyone have any input on this?

 

[deepcover6]

The way I have it is pretty close to what the instructions say except I didn't have to cut anything of the fuel line. I got a high pressure fuel line and hooked it up on to the stock nozzle coming from the fuel tank to the intake of the FMU. And then hooked up another high pressure line from the outlet from the FMU to the FPR. I think he was genralizing what he meant in the instructions by saying "Then the outlet will be connected to the fuel rail this will be shown in greater detail in the following pictures." because even in the pictures he hooks up that line right to the FPR before the fuel rails. Well I hope this clears the confusion.

 

[DooMer_MP3]

But I think Kooldino is trying to say that based on information from the other thread "A thought" that you should hook up the FMU on the fuel return line, after the stock FPR. Could be what the pictures in spool's manual show, but the wording sounds opposite to me as well. Just a heads up.

Chris

 

[duMb KeoLa]

i see what youre saying, but the pictures show where to put it and thats what i went by. if you put it before the fuel rail, you will blow your motor due to running to lean. follow the pics and youll be fine. terry, did you see this? did you mean to put it after the fuel rail and into the line going back to the tank? just trying to clarify things.

 

[Kooldino]

Yeah, the pics do look right, but like I said, the wording is iffy. It confused me and I just wanted to make sure that no one took it the wrong way and possibly damaged their engine.

 

[duMb KeoLa]

good catch man, hopefully no one did do it the wrong way. but to tell you about my experience, the shop that did my piping installed the fmu wrong. they did it the way this sounds before the fuel rail, its just lucky i caught it and switched it before hitting the bo0st hard.

 

[igdrasil]

we need this clarified, with a good picture!

My spool installation manual has no good picture about this!

 

[RevsTo9K]

A FMU definetely goes AFTER THE FUEL RAIL. In other words, it goes on the fuel line that is returning to the tank. The FMU works by restricting the amount of fuel that is allowed back into the tank. If the fuel has no where to go when it is restricted, it has no other choice than to go through the injectors. I'm sure it was just a typo on Terry's part. I'm sure he knows how it's supposed to be hooked up.

Diagram:


FUEL TANK--->FUEL LINE--->FUEL RAIL--->FUEL RETURN LINE--->FMU--->FUEL RETURN LINE--->FUEL TANK

 

[Kooldino]

Yup, like I said, it was just written a bit poorly and wanted to clear it up. Mind if I improve on your "diagram"?

FUEL TANK--->FUEL PUMP--->FUEL LINE--->FUEL RAIL--->FUEL RETURN LINE--->STOCK FPR--->FUEL RETURN LINE--->FMU--->FUEL RETURN LINE--->FUEL TANK

Look that over and make sure I didn't F it up.

 

[Little Beavis]

Looks good to me. . .I agree the wording is confusing and I had a bit of an issue with it myself.

I did just get my fuel pressure gauge today, so that will be installed shortly and everything will be "checked" and "verified". Then I can stop wondering (at least about the fuel).

To be continued. . .

 

[RevsTo9K]

That's right. I just left out two obvious parts, the pump and fpr so that it would all fit on one line. I have a patent out on my ghetto diagram so don't go spreading it around the net dammit!

 

[Norman@spool]

Yes the directions will need to be revised regarding the FMU
I wonder who wrote them
Koolindo is correct. Its relatively simple but the picture illustrates what needs to be connected.....thanks dana

 

[perfworks]

 

[Little Beavis]

Okay now, some days I feel retarded, but that picture seems to still show some of the confusion.

The Vortech FMU's bottom fitting is stamped "OUT"! The bottom fitting in the picture is labeled as "Intake (connected to gas tank)". The fitting on the side of the unit is the one that connects to the FPR and is actually the "IN" on the unit.

Gas flows through the rail, through the FPR, into the side of the FMU and out the bottom. NOTE: I did not use the ghetto diagram!

So, I've now probably confused the issue even more, right? :WTF:

 

[duMb KeoLa]

intake connected to the gas take, i guess means its going INTO the gas tank? lol thats what i think

 

[chdesign]

OK guys since I kinda brought this on here ya go....take some high pressure fuel line....run it from A. the fuel fitting on the stock fuel pressure regulator to B. the fitting on the side of the Vortec FMU.......then take some more fuel line and connect it to C. the "out" or bottom fitting of the vortec FMU and then connect that same line to the hard line where you took the stock return fuel line off of......I hope that clarifies things up some......but yes a FMU does work by restricting the amoutn of fuel flow back to the fuel tank if you install it on the fuel supply line you are choking the fuel supply.....may be a culprit of some blown motors.

 

[Kooldino]

ch-i suspected that as well.

 

[perfworks]

OK guys since I kinda brought this on here ya go....take some high pressure fuel line....run it from A. the fuel fitting on the stock fuel pressure regulator to B. the fitting on the side of the Vortec FMU.......then take some more fuel line and connect it to C. the "out" or bottom fitting of the vortec FMU and then connect that same line to the hard line where you took the stock return fuel line off of......I hope that clarifies things up some......but yes a FMU does work by restricting the amoutn of fuel flow back to the fuel tank if you install it on the fuel supply line you are choking the fuel supply.....may be a culprit of some blown motors.