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How to correct High fuel pressure on a new build STI?
How to correct High fuel pressure on a new build STI?
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Old 03-30-19, 03:04 PM   #11
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Default Re: How to correct High fuel pressure on a new build STI?

Listen to Noximous. Remove the vacuum line and start from there. Sounds like your tuner doesn't know jack shit and you should be looking for a new one
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Old 03-30-19, 04:09 PM   #12
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Default Re: How to correct High fuel pressure on a new build STI?

Quote:
Originally Posted by MY15STI View Post
The idle pressure needs to be at around 42ish psi, but it is at 58+ psi. The Aeromotive FPR can't lower it anymore.

As we’ve been eluding to, but you haven’t answered on it yet, are those numbers with the vacuum line disconnected from the FPR? Base idle pressure needs to be set with the vacuum line disconnected.
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Old 03-31-19, 10:01 AM   #13
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Default Re: How to correct High fuel pressure on a new build STI?

Quote:
Originally Posted by yamahaSHO View Post
If you turn off the pump in the tank, the surge tank will eliminate the factory hanger situation. If you cannot lower the base pressure when you disconnect power to the in-tank pump, your regulator is bad.
Just want to clarify. Do i unplug the harness on the oem fuel pump, turn on the power (not starting up), then adjust the FPR to see if it will get lower the base pressure? Thanks.
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Old 03-31-19, 10:06 AM   #14
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Default Re: How to correct High fuel pressure on a new build STI?

Quote:
Originally Posted by Noximus View Post
As we’ve been eluding to, but you haven’t answered on it yet, are those numbers with the vacuum line disconnected from the FPR? Base idle pressure needs to be set with the vacuum line disconnected.
The line was connected still. Do i need to plug the port on the FPR or the vacuum line if i disconnect it? thanks.
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Old 03-31-19, 11:37 AM   #15
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Default How to correct High fuel pressure on a new build STI?

Quote:
Originally Posted by MY15STI View Post
The line was connected still. Do i need to plug the port on the FPR or the vacuum line if i disconnect it? thanks.


That’s your problem. You remove it and can clamp it, but not required. It’s a tiny hose. Don’t need to plug the hole on the FPR.
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Old 03-31-19, 12:52 PM   #16
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Default Re: How to correct High fuel pressure on a new build STI?

You can pull the power on the in-tank pump before or after starting.

Although you set base pressure with no boost or vacuum, if you could not get it lower with vacuum, you're not going to lower it just by pulling the reference hose. Vacuum is supposed to bring pressure down even more.

If you just jump the pump in the surge tank on without starting the car, you can set pressure without removing the power to the in-tank pumps and without removing the reference line. This also eliminates the factory hanger.
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Old 03-31-19, 12:59 PM   #17
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Default Re: How to correct High fuel pressure on a new build STI?

Quote:
Originally Posted by Noximus View Post
As we’ve been eluding to, but you haven’t answered on it yet, are those numbers with the vacuum line disconnected from the FPR? Base idle pressure needs to be set with the vacuum line disconnected.
The fuel pressure is the same at 58 psi with the vacuum line disconnected from the FPR.

Should i try to adjust the FPR with the vacuum line disconnected? thanks.
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Old 03-31-19, 01:50 PM   #18
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Default Re: How to correct High fuel pressure on a new build STI?

Do what I suggested with jumping the surge tank pump to run with the car off.

If the FPR won't lower fuel pressure with vacuum on it, removing the reference line will not lower it anymore.
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Old 04-07-19, 09:41 AM   #19
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Default Re: How to correct High fuel pressure on a new build STI?

Problem solved. Got an advice from Radium, it was probably the jet pump in the OEM fuel hangar was too restrictive, creating back pressure.

So I installed a Radium fuel hangar with a WB 450, the pressure came back down, still has room for adjustment with the FPR.

Thanks everyone for your advice.
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Old 04-07-19, 02:28 PM   #20
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Default Re: How to correct High fuel pressure on a new build STI?

So... Same thing I was trying to get you to test for.
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