Fuel rail/system pressure too low

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Rp0thejester
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Re: Fuel rail/system pressure too low

Post by Rp0thejester »

Sounds like an issue with your diagbox, maybe it's not up to date or even to up to date, may need to revert it back to an earlier version. I'm sure someone here can check your diagbox version software Vs what your car can handle
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GiveMeABreak
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Re: Fuel rail/system pressure too low

Post by GiveMeABreak »

The checks on the diesel injectors for this engine simply say:

The volume of fuel returning to the diesel injectors should be a few millilitres; the volume of fuel returning to the diesel injectors increases as a function of the condition of the engine (wear).
Replace any diesel injectors that have a fuel return flow greater than that for the other injectors.

Note: After replacing one or more diesel injectors, do a diesel injectors check.

The car should be idling for 2 minutes (not revved).

Do you have any new fault codes being shown? I suggest you run another Global Test and put any fault codes up here.
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Re: Fuel rail/system pressure too low

Post by Peter.N. »

I had a similar problem many years ago with a Perkins engine, at the time I had a bulk tank as diesel was quite reasonably priced (that shows how long ago) it turned out that water was getting into the tank via an inspection plate with no gasket under it!

The problem on mine was purely mechanical, the fuel regulator valve was rusting and sticking, if I took it out and cleaned it was fine again - I wish they were as simple as that now. :(

Peter
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Re: Fuel rail/system pressure too low

Post by MGmike »

piki wrote: 26 Jul 2023, 12:21 update , so i managed to do the leak off test , i removed the end with the o ring part, i took just the hose , and it was sitting good inside the return hole.
the bottles filled so fast , in like 20 sec it reach 80 ml on the right 2 injectors
Image
Those injectors are fubar. You'll need to replace all of them or send them to be refurbished. If it was me I'd probably source a known good second hand set to confirm a fix and then have the old ones refurbished.
piki
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Re: Fuel rail/system pressure too low

Post by piki »

I appreciate all the help
i order 2 injectors , will do a test after the installation, will see how it goes.
Last edited by piki on 29 Jul 2023, 19:50, edited 1 time in total.
piki
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Re: Fuel rail/system pressure too low

Post by piki »

GiveMeABreak wrote: 29 Jul 2023, 09:20 The checks on the diesel injectors for this engine simply say:

The volume of fuel returning to the diesel injectors should be a few millilitres; the volume of fuel returning to the diesel injectors increases as a function of the condition of the engine (wear).
Replace any diesel injectors that have a fuel return flow greater than that for the other injectors.

Note: After replacing one or more diesel injectors, do a diesel injectors check.

The car should be idling for 2 minutes (not revved).

Do you have any new fault codes being shown? I suggest you run another Global Test and put any fault codes up here.
after replacing what is injector check? coding the injector?
piki
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Re: Fuel rail/system pressure too low

Post by piki »

btw the code i have is fuel rail pressure too low,P0087
piki
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Re: Fuel rail/system pressure too low

Post by piki »

Peter.N. wrote: 29 Jul 2023, 12:10 I had a similar problem many years ago with a Perkins engine, at the time I had a bulk tank as diesel was quite reasonably priced (that shows how long ago) it turned out that water was getting into the tank via an inspection plate with no gasket under it!

The problem on mine was purely mechanical, the fuel regulator valve was rusting and sticking, if I took it out and cleaned it was fine again - I wish they were as simple as that now. :(

Peter
Any idae how do i check the regulator? is that gave u the code fuel rail pressure too low?
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GiveMeABreak
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Re: Fuel rail/system pressure too low

Post by GiveMeABreak »

I don't remember putting the fault code up for you, so here it is:

Fault Code: P0087
Description of Fault: Fuel circuit : The pressure measured in the injection rail is less than the setting. The pressure measured in the fuel high pressure common injection rail is lower than the reference value for 800 ms even though the electrovalve is open to the upper limit.
Conditions for Fault to clear: Ignition switched on
Downgrade Modes whilst Fault is active:
  • Reversible deactivation of the vehicle cruise control
  • Activation of the cooling fan at fast speed
Symptoms:
  • Jerking/stalling
  • Lack of power
  • Starting problem
  • Absence of automatic stopping of the internal combustion engine (Vehicle equipped with "stop and start")
Suspect Areas:
  • Clogging of the fuel filter
  • Air leak on the fuel filter
  • Leak in fuel circuit (low pressure)
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piki
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Re: Fuel rail/system pressure too low

Post by piki »

butin the list i dont see clogged injector, after the return test i see there is 2 blocked injectors, which allows too much fuel to go back , which lead to low fuel rail pressure?
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GiveMeABreak
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Re: Fuel rail/system pressure too low

Post by GiveMeABreak »

The above is suggesting that there is the possibility of a low pressure in the low pressure fuel circuit, which would mean insufficient fuel getting from the low pressure circuit to the high pressure circuit. So according to that fault code the rail is not reaching sufficient pressure.

I'd suggest that it does need investigating by somebody with knowledge of common rail injection systems, with the correct testing equipment (caution is advised on working with HDi engines) who can pinpoint the source as to whether it's on the low pressure side, the high pressure pump or the injectors. But the clue is in the actual fault code you have on the low pressure side.
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piki
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Re: Fuel rail/system pressure too low

Post by piki »

the fault is low pressure on the fuel rail , which is the high fuel side.
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GiveMeABreak
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Re: Fuel rail/system pressure too low

Post by GiveMeABreak »

Yes, but the low pressure side first feeds into the high pressure pump and then into the fuel rail. If there's insufficient fuel getting to the high pressure pump then there is going to be less pressurised fuel in the rail:
The pressure measured in the fuel high pressure common injection rail is lower than the reference value
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piki
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Re: Fuel rail/system pressure too low

Post by piki »

yea , bu once i replcaed the fuel filter , it supposed to eliminate the low ressure circuit , isnt it?
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darbuck
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Re: Fuel rail/system pressure too low

Post by darbuck »

Your injectors are are starving the engine of fuel. It needs new or replacement injectors, those leak offs are pretty high. The diagbox is fine it's not given a good sine wave because the injectors are constantly over compensating for the sticking injectors. Your injectors are sticking which is restricting fuel flow.
Darren