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Discussion Starter · #1 ·
Could someone explain what the fuel pressure regulator is?
I am going to install a boost gauge and some people tap into the fuel pressure regulator line.
Are the fuel pressure regulator and Blow-off valve the same part? If not, what does boost pressure have to do with fuel pressure? Thanks for any feedback.
 

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looking into your engine bay from the front bumper, look at the IC. on the right side of the side facing you, is your bypass valve. off of that hockey puck looking thing, is a vacuum line shaped to a right angle, down in to the bay.

tap there. don't cut it too far down, or else it's a bi+ch to get teh T onto.

dR
 

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Basically, you want to tap for a boost gauge at a manifold pressure source. Bot the fuel pressure regulator and BOV see manifold pressure/vacuum. Either will work just fine.
 

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Discussion Starter · #4 ·
But why does the Fuel Pressure regulator need to see boost pressure? Does it need boost pressure/vacuum to operate?
I thought the fuel pump is what gives it pressure.

This is how i think it works and let me know if i am correct: Fuel pump pumps gas to the engine and the fuel pressure regulator regulates the amount of gas actually going into the engine by using vacuum/pressure as a control signal. So when you are at high rpm's, more boost pressure builds, which tells the regulator to allow more gas into engine.

Thanks for your replies!
 

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PlatinumWRX said:
In an NA car, the FP is always ~the same, but in a FI car, the boost causes the fuel to "get stuck or slow down" you need to pump up the pressure 1psi for 1psi to keep things even. Get it?

-Jim
LOL. Misunderstanding. Let me clarify, that's why it's in quotes. :D

The static fuel pressure must be raised to over come dynamic manifold pressure! Better? :cool:

-Jim
 

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They are also used in NA dry-nitrous installs. So it will raise the FP up to give the car a little more gas to compensate for the extra oxygen sucked in with the N2O. Kinda of a half fast way to do it I think.
 

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one trick i learned, instead of cutting either of these lines, just buy a short piece of it from autozone or napa. the lines are 1/4" ID vacuum tubing. just use a short 2" piece of the line you bought, and use it as an extension so you don't have to cut the factory line. then, if you have to remove it, you just pull off your T and extension and hook the totally factory line back up. gives you more room to get the T in there too. just a suggestion.
 

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phast said:
And no. it's still not better. Your understanding is flawed. The fuel pressure is not raised to overcome manifold pressure.

If there wasn't a nipple on the FPR, the fuel pressure would stay the same regardless. It's there to increase fueling under boost. PERIOD! [/B]
You are incorrect on your first paragraph. It is indeed raised to overcome boost pressure. That's the same thing as manifold pressure. The injectors spray into the very bottom on the manifold. If the manifold is seeing X psi, you need X psi more in the fuel pressure to keep a constant 43 psi pressure differential. If the line wasn't hooked up, it wouldn't raise, yes.
 

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WizardBlackWRX said:


You are incorrect on your first paragraph. It is indeed raised to overcome boost pressure. That's the same thing as manifold pressure. The injectors spray into the very bottom on the manifold. If the manifold is seeing X psi, you need X psi more in the fuel pressure to keep a constant 43 psi pressure differential. If the line wasn't hooked up, it wouldn't raise, yes.
I stand corrected. That explanation makes much more sense than .. "the fuel is getting stuck".
 

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I tapped the FPR with my DTT DCII to get boost and it works pretty well I think, one reccomendation is that you zip tie the vacum hose you install to the FPR nipple cause it's really smooth and can pop off. I zip-tied it and have had no problems since.
 
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