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Ok, I see all these guys that a do return fuel system, they place the FPR after the fuel rail inbetween the rail and the thank...dosen't that defeat the whole purpose? Because it's regulating the fuel going back into the tank VS. the fuel going in the fuel rail? Can someone please explain that part to me...

 
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The FPR holds fuel pressure until it reaches its set pressure then releases to the return line. So the actual pressure side is before the FPR. After the FPR is just a pressure release.

 
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O, so it just closes up until the fuel pressure is set and then lets the fuel go back into the return line?

 
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It keeps fuel pressure at a certain set pressure and releases any pressure over that set pressure.

 
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you can also do it the other way by using an Aeromotive FPR. It doesnt really matter on our cars because you wont ever have enough HP to outflow an AEM style one unless its a k24 full blown race car.

 
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What are you talking about?

All fuel pressure regulators work the same. Some are adjustable, some are not. Some respond to boost, others do not. But they all work the same, by restricting the flow of fuel down the return line until the desired pressure is seen on the feed side, then opening up and letting the fuel flow back to the tank.. AEM is just a crappy version of Aeromotive, but it works exactly the same, and you install it in the same place.

 
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no you do not have to there is a return on the regulator not the fuel rail. use the sides as an inlet outlet and bottom as a return. been building efi cars for many years trust me in know what im talking about. You can do it both ways, its just easier for us because then you dont hafta weld a bung on the fuel rail if you are using stock one.

 
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if the reg goes before the rail not after it. there is no exit on the rail its on the regulator.

 
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According to Aeromotive's web site, there is not a regulator that goes before the fuel rail.

According to these instructions for an Aeromotive regulator :http://216.242.145.16/usrbin/product...tors/13109.pdf

So, fuel rail to regulator, then regulator back to tank. All of the instructions I found online said this exact quote.

 
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Never heard of a regulator that goes before the fuel rail. That wouldn't let the injectors get the correct pressure.

 
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the stock one does, doesnt it??? works like that except its adjustable and boost relative.

 
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The stock Honda one? It's not adjustable, nor is it boot referencing.

None of the Aeromotive ones are, we are a direct Aeromotive dealer at work and I looked at our catalog and installation booklets, all say to be installed after the fuel rail on the return line back to the tank.

 
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I said it functions like stock EXCEPT that its BR and ADJ. I know what they say but if you only have an inlet on the rail then the system still pressurizes. The guts of those aeromotive pumps are three times the size of our factory lines so they flow fine. They wont reccomend it because then every guy with a 1000+HP turbo v8 will blow up there cars because you can only feed up to about 600hp doing it that way. The benefit is that you can do it without welding a bung to the rail and anyone with basic hand tools can do it. Think of it as the return beig like how a BOV works the boost only makes it to the manifold when the BOV is closed.

 
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Im not good at explaining myself but I have monitored my FP for the last 2.5+ years and everything works perfect.

 
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I can see what you're saying, but I can also see why Aeromotive would not recommend to do it that way. It might work just fine for a lower horsepower car like most of ours, but in a high horsepower car that uses more fuel, there would be a problem. The pressure across the rail would be kind of a secondary system since all of the fuel would not flow through the rail, but for a low flow system that would not make that much difference. That is basically how the stock system operates (since the stock reg is in the tank), and it does have some variation in rail pressure close to redline on a stock motor where the most fuel will be flowing. On a turbo motor, I can see some variations in rail pressure at higher boost levels happening if you installed the Aeromotive the way you described.

It's not that much more work to install the bung and do it the more-right way (even though the other way might work just fine for low boost), but I'd rather be safe than sorry and follow the recommendations.

 
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yeah I know its not the best way but I have been keeping a eye on it. If there are any probs I will chage it for sure. Ive seen people running 400ish on it like that so I prob dont have to worry though.