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2.5 TDI Quattro Engine wont start - manually hand prime - Starts -Cuts out????

Discussion in 'A4/S4 forum(B5 Chassis)' started by jonnycraig, Nov 13, 2009.

  1. jonnycraig
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    jonnycraig Member

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    My 2.5 TDI Quattro has decided to have a day off, turn the key, full battery, immob disarmed, plenty of diesel, it just cranks and wont start, manually squeezed fuel with the hand primer and itll start but cut out after a few seconds on idle, if I rev it a little I can keep it going, someone mentioned a non return valve? If so where is it near the filter, or primer or on the lift pump from the tank? and how much? I dread to think its the fuel pump :crying:

    Any ideas

    cheers

    JC
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  2. PW-Motorsport
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    PW-Motorsport Member

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    Sounds like main TDI pump is faulty.

    You don`t have a fuel pump as such in the tank of the 2.5, all is does is draw the fuel into the central unit in tank. It does not provide pressure to the fuel lines.

    Any air in the fuel lines when it is running?
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  3. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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  4. adamss24
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    adamss24 Active Member

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    Yeah, but its only used to prime the main chaimber with fuel from the ohter 3 sides(chaimbers) of the tank and it is NOT a lift pump. I suspect the diaphragm has broken inside the pump and as such it does cavitate...means it cannot prime itself OR the fuel runs back into the tank(one way valve defective/pinched seal)... I would tow the car and if it starts quickly then the pump might be ok.
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    huh? It sits in a swirl pot and the pump outlets connect to the fuel lines....
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  6. Drizz
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    Drizz Project Plush

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    Mine died while driving and apparantly it was a lift pump in the tank failing and starving the injector pump in the engine.
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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Exactly. Its a lift pump.
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  8. jonnycraig
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    jonnycraig Member

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    Cheers guys :) so what do you think I should do?

    JC
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  9. adamss24
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    adamss24 Active Member

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    Trust me, the "lift pump" has only been fitted on audi a6 v6 tdi quattro from late 2000 on and audi a4 b6 facelift. The b5 audi a4 NEVER had a propper lift pump. Its only there to supply the main chaimber with fuel from the other 3 chaimber so it has plenty fuel for the pick up to suck on. The main VP44 injector pump is sucking the fuel trough(self priming) and its notorious shite at it !
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  10. adamss24
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    adamss24 Active Member

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    Aragorn, read the sentence slowly as Phil english makes more sence than mine ! :faint:
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Try manually filling the diesel filter with fuel and see if it will start.
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  12. jonnycraig
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    jonnycraig Member

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    Mechanic spoke to a few people hopefully in the know!, they said its a T-Piece near the filter thats usually goes (contains a non return valve) hope its what the prob is, unfort anyone he's spoken to have told him not to accept the job, lol bit of a prob tho considering he's my girlfriends father!!! :D

    Cheers

    JC

    PS Anyone got detailed instructions on how to replace the steering rack on the V6 again most people Ive spoken to say..... its impossible without taking the engine out or say its mega expensive and make that its gonna cost loads exhale sound!!
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