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a4 tdi problem

t2myd Oct 16, 2008

  1. t2myd

    t2myd Member

    I recently replaced my knackerd engine ,i put a passat afn engine in same engine code as my original engine. the car turns over but doesnt fire ,i opend injector pipes ,nothing comes out ,is the passat pump coded ,and would it be beter puting original audi pump back on ?
  2. Fuel pumps are not coded to the ecu on the audi afn engine.
    Joking aside how much fuel is in the tank? i have found that in system that has been opened more fuel in the tank is required than in say a tank emptying through normal use.
    It sounds as if you may have an airlock someware.
    Work backwards from the pump
    Does any fuel come out of the pump return to filter pipe on cranking
    Does any fuel go into the pump?
    Is there fuel in the fuel filter?
    You will need to brim the filter up with clean fuel then bleed any air out of the top bleed screw(the one you need to undo on top when draining water out the bottom)
    The pump is a two stage mechanical pump driven off the cambelt.
    When cranking observe the fuel pump pully and shaft - it does spin the shaft as well doesnt it?
    The electronics controls the fine adjustment of quantity and timing.
    Did you see this engine running before you brought it?
    I would try these things before swapping the pump.
  3. t2myd

    t2myd Member

    i rang a couple of audi specialists ,audi dave and diesle bob ,both told me to put the audi pump back on as the passats are coded from key to the pump.where as audis are coded from key to imobiliser in the dash clocks ,therefore audi pump not coded
  4. When you change the pump be careful with the bolt holding it on at the back - If you drop it it fits nicely behind the waterpump/ thermostat housing which means dropping the coolant and moving the housing.
    From the above note you may guess that I dropped the bolt!

    Do you have vagcom - its a long shot but is it possible for you to code an audi key to a passat fuel pump?
    I know that vagcom can code new ecu's for the Audi afn engine as I have done two.
    If it turns out you do have to change the pump make sure that the filter is fully primed with fuel and first crank it with the pump - injector pipes slack enough for fuel to come out.
    This should help reduce the time you have to crank the engine to get the fuel flowing with no air.
    It can take a suprisingly long time to get them started after the fuel pipes have been open so dont think its all doom if it doesnt go on the click.
  5. t2myd

    t2myd Member

    your right that bolt was a tw*t.you need to have miniture hands to hold the nut ,,i havent got vagcom im lucky my mates a audi mechanic.im also banging a new fuel filter on .audis are a pain in the ar*se when they go wrong ,be beter of with my grandads nissan micra !!!

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