1.8 TDCI Focus Random spikes in fuel pressure

[rg1642]

Hi all,

My 1.8 TDCI 2006 Mk2 had a new fuel pump fitted 18 months ago by Ford at the staggering cost of £1800. (Cambelt done at same time) Last week I got a few seconds of rough running, engine systems fault warning, and the red light. Nothing for a few days then the same again, twice in one day. Nothing again until yesterday then the same again. Stuck the scanner on this morning and it was throwing up codes for Rail pressure too high and pressure regulator fault. Is there anything that could cause this other than another pump being on the way out?

:(

[Povo]

Maybe the pressure sensor is reading badly?

[Tdci-Peter]

13 hours ago, rg1642 said:

codes for Rail pressure too high and pressure regulator fault.

The fuel pump pressure is controlled by two valves.

The IMV or flow regulator acts between the 1st & 2nd stages of the pump, and by depriving the 2nd (HP) stage of fuel, it makes it into a variable displacement pump, that only supplies the fuel needed, so not wasting power pumping excess fuel up to 1500Bar.

The PRV or pressure regulator is on the outlet of the fuel pump. It removes surges of pressure that are too high, caused by the IMV being too slow acting or to imprecise to cope with rapid demand changes.

First suspect here seems to be the PRV. This is now a replaceable part. See:

http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&mvsub=1&_mcatda=true&selfil=2%2C3%2C1%2C9%2C8&selvel=Ford~Focus~2006~MK%20II%20%5B2004-2016%5D~1.8%20TDCi&_nkw=fuel pressure regulator Ford Focus 2006 MK II 1.8 TDCi

Hopefully it is not the pump itself at fault, if excess pressure is the problem. It could be the sensor (as Povo above suggests), this is also now available as a not too expensive part. It could be the wiring to it or the plug. But I would guess that PRV (or its wiring or plug) is more likely in this case.

Out of interest, I have been monitoring the performance of my pump using Forscan. This can give a detailed record of pump performance in real driving conditions. I monitored Accelerator position, rpm, speed, fuel rail pressure, and IMV duty cycle on the last run. It all looked quite sensible. If you wanted to do this, it just might give some extra clues.

Fuel run below. FRP is fuel rail pressure. APP is accelerator, VCV is the IMV duty. The high pressure bit was going flat out up a reasonable hill on a dual carriageway. (Might have gone a teeny weeny bit over 70, but I corrected that as soon as I noticed!)

[rg1642]

Awesome stuff buddy :) . I got Forscan so I'll run it while I'm out for a few days and see if it happens again. Sods law it will be ok for a few days or weeks now. LOL but at least I know the way to go. I assume I am looking for a big differentail between the FRP & pressure regulator readings?

[Tdci-Peter]

3 hours ago, rg1642 said:

I assume I am looking for a big differentail between the FRP & pressure regulator readings?

I can not recall if Forscan had a PID for the PRV itself.

I think that the clue would be spikes on the FRP PID when releasing the accelerator pedal fairly quickly, eg a gear change. If this happened often, and the spikes seemed too large, this would show a poor PRV operation. If the trace was normal, then got spikey at the time that a DTC appeared, this would also be helpful. You can monitor DTC count as well, this would show exactly when a DTC happened.

But if it is intermittent, then catching it happening will be luck of the draw, and may take some time!

 

[rg1642]

Ran for an hour out today. Not a peep out of it. LOL next time I drive without it connected you know what will happen :)