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Why wont my TDi start?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by PiloTT, Jan 13, 2009.

  1. PiloTT
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    PiloTT Member

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    its been garaged for about 6 weeks and when I tried to fire it up it started for a few seconds then stopped. Now it wont start at all! It cranks over OK on a strong battery but sounds a little different. Just flooded maybe? Will it do any damage trying to crank it?

    its a 2.0 170DPF
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  2. Amchlolor
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    Amchlolor Active Member

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    I thought fuel-flooding was a thing of the past, when carburettors ruled the earth, so it's unlikely to be that.
    Isn't it more likely to be the diesel fuel itself going 'off'?
    I know petrol can go off pretty quickly, I've seen it happen in laid-up motorbikes.
    Diesel will absorb oxygen and moisture from condensation, especially if your tank wasn't full in the first place.
    If it's absorbed 'contaminants', there's a chance one or more of your fuel filters are now clogged.
    Hey presto, your car will turn over but no fuel is getting through.
    Whether you'll be able to fix it yourself is debatable.

    Cranking it won't do any harm.
    In fact, it's better for a laid-up engine to be cranked over before firing, as this will allow oil that has drained into the sump to circulate.
    On a motorbike, you do this by turning it over with the killswitch set to 'off'.
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  3. SunnyDlite
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    SunnyDlite Six speed Shimano

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    i had a similar problem with my old veccy, i really needed the car and wasnt about to get a taxi so cranked the pants off it till it lived, reving as the engine turned over, (not sure bouncing about back and forth in my seat helped but it made me feel like i was helping) till it came back to life with tonnes of black smoke pouring out the back

    was fine after that just took it for a quick spin round the block.

    not sure if thats the best or even healthiest way round it but if your gonna give it a shot make sure u roll it outta the garage, or be prepared to coat everything in black ;)
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  4. PiloTT
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    PiloTT Member

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    Well thanks SunnyD... that seemed to do the trick. You were not wrong about the amount of black smoke. Only seemed to start firing once I cranked with full throttle.


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  5. Macduff
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    Macduff Member

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    Not true Bowfer. You can flood a modern injected petrol engine by starting from cold then shutting it off quickly e.g. if you quickly move a car. I had this issue on a Lupo we had a few years back when I had to move it just a few feet. Also had it on my VFR when SWMBO started it by accident. After that I always drove the car at least a couple of miles even if I only needed to move it a short distance.

    BTW, I've never had a bike that could be cranked with the kill switch off. Do they exist?

    That sounds like the engine was flooded. On a petrol engine if you crank the motor with the throttle full open it leans it out so much that you effectively dry out the cylinders and plugs so it will eventually start. I expect the same principal applies to a diesel.
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  6. Khufu
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    Khufu Active Member

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    Could be the filter, thanks to the addition of bio fuel to diesel any mosture in the fuel/air helps turn the bio diesel into a gunge like gel that blocks the filter.
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  7. SunnyDlite
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    SunnyDlite Six speed Shimano

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    cool glad it worked :)
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  8. Amchlolor
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    Amchlolor Active Member

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    Petrol's as bad.
    I've just stripped/rebuilt a racing motorbike that a bloke had sitting in his garage for ages.
    Honestly, you wanted to see the mess the carbs were in.
    Full of what could only be described as 'snot'.
    Yuck.
    #8

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