Any tips on what might cause a VR6 to be a bit slow to fire when hot ?

  • Most of the times when my 95 VR6 is warm I will have to crank it for a little while before it fires.


    Any tips on what might cause this?.


    I get no error codes with VAG-COM, coilpack is as far as I know "recently" replaced).


    Will ex the crank position sensor cause something like this ? (and not show any error codes ?).


    Or anything else causing it? - It seem like it will always start - but when hot takes some more cranking..., so more annoying than a major problem :)

  • This maybe a problem of a valve in the fuel pump. The valve holds pessure in fuel pipe and if the valve ist broken the fuel runns back to tank. The fuel vaporize and the Motor will not start.

  • This maybe a problem of a valve in the fuel pump. The valve holds pessure in fuel pipe and if the valve ist broken the fuel runns back to tank. The fuel vaporize and the Motor will not start.


    Would that mean changing the complete fuel pump ? (and is it a "known" problem )?


    Also where would you buy such a pump online in Germany ? (OEM/VW brand) - just want to check price as it's da** expensive up here :)


    Also is there any way I could check if this is the culprit ?

  • You dont have to change the pump. You can fix it with a external Valve behind the Pump.
    I had also the same problem on my 95 VR6. It´s a produktion problem by VDO and they fixed that problem in 06.95.


    You can check the valve. Pull up the upper fuel hose at the Fuel Injectors Bridge and blow air in to the hose. If you can blow air, the Valve is broken.

  • where would you get this valve if it's broken ?



    If i understand correct I could just unplug the upper fuel hose coming intp the fuel rail - and I should not be able to blow back air into it ?.....


    thanks again for the answer :)

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  • Right! It exist even a repair kit with a part number. A 25-35 cm hose with a valve. Unfortunately i lost the Part number and i can´t find the webside where i found the information.
    It´s not only a Corrado problen. Golf 3 and Passat had also problems with VDO fuel pumps.


    Can't get the image to work - is it of the repair kit or ?.


    Was this kit available from VW too or ?

  • If anyone happen to know the part number for this thing, I'm *very* interesting in knowing :)


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    I'v just put in a non-return valve from just after the fuel pump, and now theis problem seem to be gone, so thanks very much for this tip! :)

    Einmal editiert, zuletzt von Corradoman () aus folgendem Grund: aus 2 mach 1

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  • What also might cause the engine to fire slowly when its hot, is that the intake isnt fully airtight. (since its controlled by the lambda sensor when its hot, rather than just dumping a load of fuel into the engine as it does when its cold. so when the engine is hot, the mixture is much more important.


    What also could cause it, is a dirty fuel filter. then again, if thats the cause, i'd excpect it to fire slowly with a cold engine aswell.

    Ich hab mir meine meinung schon gebildet, also bitte belästigen Sie mich nicht mit Fackten.

  • Fuel filter on this car have been replaced so quite new - and it had the same problem with the old filter as well, so doubt that is the case with my car.


    thnx for that tip though :)

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