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444K Low fuel rail pressure.

Discussion in 'Wheel Loaders' started by PJ The Kid, Dec 4, 2017.

  1. PJ The Kid

    PJ The Kid Well-Known Member

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    I have a 444k coding for low fuel rail pressure, I don't have any way to test the pressure as of now and was wondering if it is common for the rail pressure sensor to go bad, I can get the serial if needed. I also don't have any shop manuals for the unit at the moment as I am not the one that normally does the repairs to it aside from some general maintenance.
     
  2. Bls repair

    Bls repair Senior Member

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    Running any different after you through the code?
     
  3. partsandservice

    partsandservice Senior Member

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    Often a low rail pressure code occurs because of a fuel supply issue. Clogged fuel filters Fuel hose clog , suction line leaks or lift pump issues. No or not enough fuel to the high pressure pump means no rail pressure.
     
  4. PJ The Kid

    PJ The Kid Well-Known Member

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    That was going to be my next question, I'm not very knowledgeable on common rail setups. I replaced the fuel filters and the rail pressure sensor, but the machine is still coding and either dying, or derating. Wondering if a lift pump could cause the issue before I throw one at it.
     
  5. partsandservice

    partsandservice Senior Member

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    Just go old school to fix this code most of time,. Never mind it is a common rail. Check for suction leaks. Run it till it dies out , shut it off and pull the fuel filter , if they are not full you know you have suction leaks. Blow the main supply line back to tank, check any 90 deg fitting for debris. Check the orings in the filter head. If there are any metal lines on the suction side check the grommet s for deterioration.
     
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  6. PJ The Kid

    PJ The Kid Well-Known Member

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    Will do, after I changed the filters, it has not died, but is still flashing a warning and sometimes the idle will fluctuate. This model also has the electric low pressure fuel pump (lift pump) instead of the cam drive pump. The codes I got -
    1569.31 fuel derate
    94.18 low pressure fuel pressure low
    157.1 fuel pressure low
    1347.1 fuel system failure
     
  7. partsandservice

    partsandservice Senior Member

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    94.18 would indicated supply pressure low which could cause the other codes, the 157 low rail pressure, 1347 fuel pump code and the fuel derate condition exhaust. It is possible that the rail relief is leaking. The rail pressure relief is threaded directly in the rail, it will have a low pressure return line going to it. Remove this line and crank engine while observing , at idle no fuel should come out of the relief,. Not even drips. Fuel will come out of the removed fuel line and that is normal. Do not remove or slacken any of theI high pressure fuel lines while the engine is running. The one i am speaking of will take a 9/16 wrench to remove.
     
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  8. thepumpguysc

    thepumpguysc Senior Member

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    GREAT diagnostic work P&S..
    I've also been seeing collapsing fuel lines coming in this year..
    You'll need a gauge or computer hooked up to find it.. OR if its bad enough, you can actually SEE the rubber lines sucking down..
     
  9. PJ The Kid

    PJ The Kid Well-Known Member

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    Ended up being a crimped supply line and a bad sender in the tank, sender was sucking air when it was under about 1/2 a tank and the line was pinched over
     
  10. thepumpguysc

    thepumpguysc Senior Member

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    GOOD DEAL.. glad ya found it..