Peugeot fuel pressure

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Peugeot fuel pressure

Postby colingibbs1 » Sun Jan 10, 2016 10:29 am

Hi all. First post so here goes.
I have taken on a problem vehicle as is seem to be a real head scratcher. Peugeot boxer van 2.0hdi engine code RHV.
It has a p code P0191 fuel pressure inconsistent. I have checked the fuel pressure switch in the rail, I have 5v supply, ground and signal in the middle. I get 0.5v with ignition on and 1.25v on idle, this rises to 3v when revved. Not yet took a reading while driving under load. All readings have been taken from the ecu end of the wiring harness to check integrity of the wiring. According to my information this is all normal.

I have another machine reading fuel pressure while driving. Pressure on idle shows a min of 277bar, at around 3000rpm the van cuts out and flags up the code, fuel pressure at this point is 867bar. Vehicle will run in limp mode after this.
Any suggestions will be greatly received.

Regards
colingibbs1
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Re: Peugeot fuel pressure

Postby Budgie » Wed Jan 13, 2016 9:47 am

Hi, from your description I am concluding that the fuel pressure is not being maintained at a level that the PCM is happy with. This obviously could be too much or more than likely too little pressure. When road testing and the fault occurs have a look at the duty cycle to the DRV whilst monitoring fuel pressure this should give you some idea as to what is happening. This info should be available in live data.
You could use your scope monitoring rail pressure voltage (signal wire), DRV using a duty cycle maths channel converting from the control wire of the DRV.
IF it is lack of pressure, then obviously there are many reasons for lack of pressure, eg fuel supply to and from filter and through to pump (restrictions, air ingress etc.), excessive injector back leakage under both low and high fuel pressures, sticking DRV, faulty high pressure relief/safety valve (if it has one) and of course the ability of the HP pump to actually make pressure which is fairly straightforward to test, the other consideration is can the pump produce the required volume of fuel, although this is fairly rare in my experience.
Hope some of the above helps .....
Gary
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