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Unread 12-27-2009   #1 (permalink)
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Default low fuel pressure on 2001 mustang gt

my fuel pressure is reading 28 on idle. i just replace my fuel pump and my fuel pressure is still reading 28. Anyone no what the problem can be ? thanks
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Unread 12-27-2009   #2 (permalink)
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Where and how are you measuring fuel pressure? It could be a bad FPRS fuel rail pressure sensor.

At idle your fuel pressure should be ~32 psi

At idle with your FPRS vacuum line disconnected and plugged, fuel pressure should jump to ~40 psi.

I would look at your FPRS, they are the same part # for V6, GT and Cobra if I remember correctly.
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Unread 12-27-2009   #3 (permalink)
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Fuel filter first.
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Unread 12-27-2009   #4 (permalink)
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im useing a fuel pressure gauge tester i got from autozone. all my other cars read 40-45 my mustang read 28 at idle. i think it might be the sensor cuz i already replace the fuel pump and fuel filter. is the sensor located on the fuel rail on the driver side?
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Unread 12-27-2009   #5 (permalink)
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Yes, that's the sensor, it has a vacuum line on it and a wire connector.
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Unread 12-27-2009   #6 (permalink)
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Blew my first FRP sensor.....DANG! - Page 3 - ModularFords.com

There are part #'s listed in this thread which may help.
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Unread 12-28-2009   #7 (permalink)
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Thanks I'll make my order 2day
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Unread 11-04-2010   #8 (permalink)
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Default low fuel pressure

Hi Everyone
I am also having a fuel pressure issue on my 2001 Kenne Belled GT
my Autometer fuel pressure gauge reads 20Psi at idle, the fact that the car runs well leads me to believe the pressure sender for the gauge is bad. What opinions do you guys have about this?? Could I have a fuel rail pressure sensor problem? thank you frank
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Unread 11-04-2010   #9 (permalink)
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WOW. The fuel pressure is intake vacuum referenced. This is called delta pressure. It is SUPPOSED to read low at idle. Remember that the intake is under VACUUM at idle.

40 PSI delta - intake vacuum = atomspheric(gauge) pressure.

Under boost, the higher pressure inside the intake will ADD to the gauge reading. For example if 5 PSI of boost, the external gauge will read 45 PSI and this is correct.

What happens if you disconnect and plug the Fuel pressure vacuum line for a test? Does it jump to 40 PSI?

Note, NEVER drive a car with the fuel pressure reference line disconnect. Esp in a boosted application.

If you do not understand the difference between Intake referenced (Delta) and atomspheric (gauge) then this problem will elude.
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Unread 11-05-2010   #10 (permalink)
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Default low fuel pressure

Hi WM Burns
Thank you for your help when I disconnect and plug the line pressure goes to 30 Psi still 10 Psi low is this starting to look like a bad sender to the fuel gauge?? Frank
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Unread 11-05-2010   #11 (permalink)
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Being exactly 10 PSI low is strange. However, boosted applications are hard on fuel pressure sensors. Consider replacing the unit and CLEANING the electrical connections to the sensor. Pay attention to the extension harness as well.

When the vacuum reference line is disconnected and plugged, the pressure should go to 40 PSI unless it has been altered by the tune (unlikely).

After replacement, under boost, the gauge fuel pressure should be above 40 PSI.
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Unread 12-14-2011   #12 (permalink)
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Quote:
Originally Posted by mikeo6000 View Post
Thanks I'll make my order 2day
well hold on .i just replaced my frps and my fuel filter.before fuel filter 28 after it read 30 still not high enough,now from reading your situation i dont know wether i should change my fuel pump..does anyone know what a low fuel pressure switch is?also i reset or erased the p0193 code but it pops back up after 30 seconds or so
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Unread 12-15-2011   #13 (permalink)
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For the P0193, there's is a possibility this is caused by a larger fuel pump WITHOUT a proper tune. If this is a stock fuel pump, the odds favor an electrical issue to the FRPS itself.

If the FRPS has already been replaced, focus on a blocked/leaking intake vacuum reference line or a wiring fault to the FRPS.

Finally, this could be a bad fuel pump or use of a fuel pump designed for a return system in a return-less application.

>>
P0193 - Fuel Rail Pressure Sensor Circuit High Input (FRP)

The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for high voltage. If voltage were to fall below a calibrated limit and a calibrated amount of time during testing, the test will fail. FRP signal shorted to
  • VREF or VPWR.
  • FRP signal open (gasoline only)
  • Low fuel pressure (NG only)
  • Damaged FRP sensor.
  • Damaged PCM.
  • High fuel pressure (caused by damaged fuel pressure regulator) NG.
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