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low fuel pressure on 2001 mustang gt

33K views 15 replies 8 participants last post by  Troyboy22 
#1 ·
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
 
#2 ·
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.
 
#4 ·
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?
 
#12 ·
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
 
#8 ·
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
 
#9 ·
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.
 
#11 ·
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.
 
#13 ·
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.
 
#14 ·
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.
I’m having a low fp aswell also seems to drive better in 3-4-5 gear vs 1-2
An seems to die when I come to a stop an try to take off.
replaced IAc, maf, injectors. Fuel pump fuel filter. FRPS
Checked all plugs.
 
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