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PSUrivie 05-24-2011 02:40 PM

08+ Returnless Fuel System
I'm curious to know how in the world the 08+ fuel system works. There is no fuel rail pressure sensor on the 08+. I thought that sensor was the heart of the returnless fuel system. The sensor allows the ECU to calculate the pressure drop across the injectors, correct? So, if that sensor is not there, how is the ECU calculate the pressure drop across the injectors?

iminhell 05-24-2011 07:43 PM

Interesting ...

Here is what I found for the 2007 and older Duratec:

Verified by a pic of a 2005 Focus Duratec engine:

The 2008+ does not have the sensor, as you said:


My thought right now is the sensor was simply moved. I notice the newer cars have an added heatshield on the firewall. Maybe it's back there?

It is possible that they don't have one at all. If you know the duty cycle and flow of the pump as well as the injector duty cycle and flow you can figure out the theoretical fuel rail pressure. The older ECU's did this already. Maybe Ford engineers got enough data they where able to build a flow/pressure map that was perfect, nixing the need for the sensor. But having a redundancy in the system would of been a good idea IMO.

tetra 05-25-2011 10:36 AM

Also what I want to know is how there is no "fuel filter" on my 2009.
It's just a screen. Supposed to be lifetime durability.

ryuclan 05-25-2011 10:55 AM


Originally Posted by tetra (Post 3683316)
Also what I want to know is how there is no "fuel filter" on my 2009.
It's just a screen. Supposed to be lifetime durability.

I believe the filters are inside the fuel pump and it is a lifetime filter. the fuel was always filtered twiced anyway going through the sock on the fuel pump then the filter outside the fuel tank.

1turbofocus 05-25-2011 12:30 PM

There is no sensor to measure the psi drop across Inj its basicly all dont in the fuel pump assy and they carry much higher fuel psi 56-58 psi

I have never had the chance to have a fuel pump assy out to look it over but guessing there is an inline psi regulator built in

Correct the filter is the sock filter on the fuel pump , kinda silly to have 2 filters


daveyboy 06-15-2011 01:05 AM

I belive tom to be correct. the sensor is in the fuel pump assembly

AlteredZ 10-04-2016 12:15 AM

Has this ever been verified - that the the fuel pressure sensor is in the fuel pump assembly? This is the part that says fits my 2010 Focus SE 2.0L (using my VIN to look it up). Unfortunately, there is no diagram showing where this part goes: 2010 Ford Focus Fuel Injection Pressure Sensor |

PSUrivie 11-19-2016 09:30 PM

I was never able to 100% find a fuel sensor that is common among the old Foci. From what I understand, the ECU is commanding the fuel pump how much fuel is required for the engine given a certain load. Hence the reason for no PID in Livelink.

To get around this I installed a AEM fuel pressure gauge. The gauge has an analog out. You can add an equation to Livelink to then log you fuel pressure.

AlteredZ 11-19-2016 09:36 PM

I ended up removing the tank (not very difficult - easier than cutting a hole in the floor!) and removing the fuel pump module and taking it apart. There was no separate sensor in the pump module, just a pump and a fuel level sending unit - no wires for any other sensor. No other sensor in the tank anywhere. So I agree - the ECU must be modulating the voltage to the pump - strange to not have a sensor somewhere for feedback. I could find nothing in the entire system as far as a pressure sensor, besides the EVAC pressure sensor in the vent line from the tank to the fueling inlet. That sensor was bad, and was causing a code (0452 I believe) before I replaced the 3-ended line and sensor assembly.

Caterpillar 08-23-2019 02:14 PM

2009 Focus low power and trans drops out of overdrive
Been having driveability problems-low power and setting code p0171 for lean exhaust.
have changed many parts including the fuel pump - transmission drops out of overdrive and will not shift up unless I clear the code with my data reader. Always has a code for lean exhaust bank 1. Any Ideas , replaced fuel pump, both oxygen sensors and the mass air flow sensor.

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