Question on Return Lines.......

731 Views 7 Replies 5 Participants Last post by madwax, Jun 22, 2007

madwax

Discussion Starter · Jun 16, 2007

I have seen a few variations here as to the types of return lines available for our cars, but I am confused on one thing. On mine the fuel flows to the regulator, excess is sent back and the proper psi is sent to the rail. Wouldn't it make more sense to send it back to the tank after it goes through the rail so it can be used if needed? Why would mine send fuel back to the tank before it even reaches the rail? Is this wrong? I would think the return line should be after the fuel rail to send excess fuel back and not before it, is there really a need for a regulator, can the fuel just flow straight through to the rail and excess sent back from the other end of it?:scratchhe

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Turbocruiser13

· #2 · Jun 16, 2007

I'd say atleast 90% of the returnline setups out there today are after the rail...can't say that I've even seen one before the rail on an srt yet. Anyways, yeah it does make sense to me to have it after the rail to be on the safe side but it's hard to say wether that's actually practical or if we're just being over cautious. With the regulator, I think the problem would be your pressure. If there is no stopping point for the fuel i.e. it just goes in a loop, it would be hard to keep a constant pressure that way. the fuel may just fly straight through the rail and won't give enough time for the injectors to pull the fuel into the manifold...just seems kinda logical to me that way...but hopefully someone with some more experience can chime in on that

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madwax

Discussion Starter · #3 · Jun 17, 2007

Mine is the AGP one and i am sure i installed it correctly, near where the stock line comes up the firewall in the engine bay on the passenger side is where the regulator is mounted. The factory line enters into it, the return line out the bottom and back to the tank, and then the gas line to the rail. The regulator is mounted to the strut tower just like in their diagrams, which I have long since lost, lol! But I have been looking at it and wondering why the fuel is to return before the rail and not after, seemed odd is all.

Bad pic I know but is all i have for now, but you can see the regulator on the passenger side tower and the line going to the rail.

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SpeedEuphoria

· #4 · Jun 17, 2007

I think you may be confused on which is the feed and return lines. It should feed to rail, rail to fpr, fpr back to tank. Yours should be right or I think it would act funny/be a prob.

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uncommon©

· #5 · Jun 17, 2007

agp return lines have the regulator before the fuel rail .... most other return lines have it after the rail.... according to agp, a return line will flow the same regardless of the location of the regulator (before or after the rail)

in other words, yes you installed your return line correctly ... and yes it's going to work fine

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uncommon©

· #6 · Jun 17, 2007

SpeedEuphoria said:
I think you may be confused on which is the feed and return lines. It should feed to rail, rail to fpr, fpr back to tank. Yours should be right or I think it would act funny/be a prob.

agp's return line is NOTfeed<->rail<->fpr<->tank

agp's return line IS feed<->fpr<->feed<->rail ... then the line off the bottom of the regulator the line should run to the tank for the actual RETURN LINE .... also, on agp's return line you dont need an 03 style rail or any aftermarket rail for that matter - their system can be used with the stock 04/05 non-schraeder valved fuel rail

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Pit Viper

· #7 · Jun 22, 2007

with agp's setup, think of it the way your turbo works.

The fuel regulator is like a wastegate. on the turbo, the air runs through until the pressure gets to the specified point, then the wastegate opens and dumps the excess. On their fuel system, the fuel runs straight to the rail until the pressure gets to a specified point, then the regulator dumps it down the return line.

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madwax

Discussion Starter · #8 · Jun 22, 2007

Pit Viper said:
with agp's setup, think of it the way your turbo works.

The fuel regulator is like a wastegate. on the turbo, the air runs through until the pressure gets to the specified point, then the wastegate opens and dumps the excess. On their fuel system, the fuel runs straight to the rail until the pressure gets to a specified point, then the regulator dumps it down the return line.

Got ya! Thanks!:thumbsup:

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