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  1. RossSline

    RossSline New Member

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    Evening folks.

    My 3.0ltr V6 ASB engine'd A4 recently flashed up a fuel pressure low code and the engine died.
    Several attempts to restart the engine have proved unscucsseful so I had it towed home.

    Since then I have done some rudermentery diagnostics and found the metering valve on the side of the high pressure pump to be faulty. So I stripped the pump off, replaced the valve and refitted.
    However it still won't start.
    Assuming I'm having a air lock problem (despite back filling the pump with fresh diesel) I have hard wired the lift pump in the tank and placed a second pump inline just after the fuel filter and purged the system and am happy fuel is in the rails and where it should be, but again she refuses to start.
    Add some easy-start into the mix and it'll run but cuts out as soon as you stop feeding it.
    I have pulled the plug on the crank sensor and checked it over with a meter and am reasonably happy its ok.
    To double check the hight pressure pump I pulled the top most valve off so I could see inside the body and can confirm its in good shape, full of fuel and oscillating when cranked.

    If you asked me to bet I'd say the pressure isn't high enough as it does squirt fairly hard out of the rails its certainly not the huge pressures they say the rails are supposed to be at.

    I am pretty much out of ideas. I have a new pressure sensor coming but since I have fitted the new metering valve and cleared the codes its not returned.
    Does anyone have any suggestions for my next step?

    Thanks
     
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  3. Paul battams

    Paul battams Active Member VCDS Map User

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    I’m not sure but if you pull the metering valve plug then try crank I’m not sure if it doesn’t give the pump full pressure also try cracking injectors near injector if that makes sense not just on the fuel rail
    Is the fuel filter new/old blocked maybe tank ran near empty **** in fuel lines?????

    Good luck


    Sent from my iPhone using Tapatalk
     
  4. BakPak

    BakPak No Gear

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    Check the fuel pump drive belt hasn't snapped. This happened to my 3.0tdi ASB earlier this year.
     
  5. BakPak

    BakPak No Gear

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    Sorry just read your thread properly, not the pump belt.
    The mechanic who replaced the belt said the engine was a right pig to get going again. He said he cracked the injectors on the rail connections but it still took a while before it started.
     
  6. BakPak

    BakPak No Gear

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    The chap I bought mine from is a mate and I remember him telling me he changed the fuel filter. He spent ages trying to start the engine and ended up getting someone to tow him for 100m or so to get it going.
     
  7. RossSline

    RossSline New Member

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    Thanks for the replys,

    Paul - I'll try pulling the plug and see what happens. The filter is reasonably new - also made the mistake of not filling the new one and that gave me starting problems, but nothing like this.

    BakPak - I've cracked all the injector pipes and am getting fuel but not under huge amounts of pressure.
    I've also thought about pulling it and dropping the clutch to try and get it running too.
     
  8. BakPak

    BakPak No Gear

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    When you say you have fuel pressure, is that pressure building by cranking it over? I know it's unlikely but the fuel pump drive belt is intact?
     
  9. RossSline

    RossSline New Member

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    If I run the lift pump and my inline pump I get some fuel pressure, then when I crank I get more but certainly the huge pressure the rail runs at.
    The belt is fine, I put a new one on when I refitted the pump - I am wondering if the sproket isn't fully on the pumps splindle and is slipping slightly.
     

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