Focus ST170 fuel supply issue

Hi all,
 
My Focus ST170 has been playing up over the past week and I am having difficultly diagnosing the issue. I was wondering if anyone could give me some advice...
 
Last weekend I was out driving about and the car starting dying whenever I tried to give it a boot-full, I decided to fill the car up with petrol and go from there. Unfortunately this did not make a difference. I got about 20kms toward home when the car decided to completely die. I primed pump by turning the key on and off several times and eventually I was off again, although I could barely get the car over 30kms and hour. Long story short I eventually limped home.
 
I got a mechanic who lives down the road to check the fault code and it registered P0190 - Fuel Rail Pressure Sensor Circuit Malfunction.
 
Apparently fuel pumps are common to die in these things so I automatically jumped the gun and bought a new aftermarket fuel pump. I put it in the next day and I was away again.. until 4 days later when the same symptoms began to re-appear. It has not got bad enough to register another fault code, but I am nearly certain it is the same issue.
 
I might also add that I had changed the fuel filter about 2months prior to the main event as the car seemed to be suffering from fuel starvation sometimes when I was driving it hard. I changed the filter with the pump again last weekend.
 
I got a lend of the diagnostic scanner from the mechanic again yesterday afternoon. I went for a drive watching the fuel pressure (The focus runs a returnless fuel system and the fuel pressure is regulated electrically by a sensor on the fuel rail - from what I understand) and as soon as I got on the throttle the fuel pressure would go from about 300kPa to just about nothing. So it definitely appears to be a fuel issue.
 
What I can't quite decide is if the new pump I got is faulty or if it is the fuel pressure sensor that is faulty. The figures I was getting from the diagnostic tool makes me believe that the fuel pressure sensor is working correctly as the readings it was giving were plausable, although there was a fuel pressure sensor voltage reading that was constantly zero, so I am not sure if that points to an issue or not. Unfortunately I have been unable to track down a workshop manual as yet.
 
I have checked the wiring as best as I can and everything seems ok. I really hope the ECM is not at fault.
 
Sorry for such a long post. As always any help would be appreciated!
 
Cheers,
 
Damion

Hi Damion
I used to own a ST170 before it got smashed into on Boxing Day, the only fault(s) i had was the electric throttle intake runner pivot to snap on the inlet leaving it to run on the short runners. I found this site that may help in some way http://www.fordst170.co.uk/known.php
BTW, mine had 115,000km when the power steering pump blew up...none in Aust and to rebuild was $1500 thru Ford!!!!! , ended up buying a recon unit from a UK RS dealer at  140pounds($250). 
If you need new parts, ie brake rotors , pads, etc etc  i suggest buying from USA, their Focus is called SVT (ST170) .
 

Definately worth checking the Orings etc around the fuel pump/filter module, a pinched or leaking oring on the pressure side of the pump will cause the same symptoms.

What are the symptoms of blocked injectors?
 
Interestingly, the issue isn't as apparent when the car is cold.
 
Cheers.

Hi everyone,
 
I cut open the original fuel filter and it was fairly clean. I also jacked the car up tonight and checked the fuel line down the length of the car, it is undamaged.
 
I checked the tank breather system and it appears ok. I guess if I go driving around with the fuel cap off I will soon find out if it is a breather related problem?
 
I will check the injectors on the weekend when I have better light, although I don't think it is the injectors as the fuel pressure is low in the rail prior to getting to the injectors.
 
Another question, is it likely that the ecu will have a failsafe for the fuel pressure sensor? If I were to disconnect the fuel rail pressure sensor (electrically) would the ecu bump up the fuel pressure to some known safe pressure? Just trying to find a way to rule it out.
 
Thanks.

P0190 Fuel rail pressure (FRP) sensor - circuit malfunction Wiring, FRP sensor, ECM  
Put a mechanic guage on it and check the pressure...

How many wires does the fuel pump controller have? They are easy to test generally as you can bypass them.

Sounds like the same set up as Turbo and 6 Cyl Subaru's run... The wires to the unit will be 12v from fuel pump relay or fuse,GND, +ve out to fuel pump, -ve out to fuel pump, 2 wires from ecu, one will be a reference voltage and one will be a switching to gnd to produce a variable duty output....exactly like an injector would use. The ecu sends the injector pulse type duty signal to the fuel pump controller, this varies the voltage output to the pump. I have just finished diagnosing and repairing a car that had the same issue. I found that when operating normally at idle etc there would be around 8v going to the pump, when under load/accelerating the voltage should go up to 12vish. You can also check the signal from the ecu easily with an oscilloscope, actually if you have a 4ch scope, you can monitor the input voltage and output voltage as well...very easy to see where the issue would be in that case.