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fuel pump on its way out, options?

Discussion in 'A3/S3 Forum (8L Chassis)' started by karl210, Nov 11, 2012.

  1. karl210
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    karl210 Member

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    Im quite sure my fuel pump is on its way out, its not too bad yet but once a week it coughs on startup and 30% of the time its down on power and im getting pretty horrendous mpg. So im wondering what my options are? its a stage 1 amk engine.
    They do a budget pump for £90 at ecp, is this an acceptable route to go without spending £250+ or should i get an inline pump? aswell as the intank or instead of? Just looking for my options really as i dont want to spend a ridiculous amount on it as its already draining my wallet.
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  2. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Have you scanned for faults? bad MPG isn't related to a faulty pump... normally an airleak or EGT probe issue...

    Have you had any data logging done in VCDS?

    <tuffty/>
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  3. karl210
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    karl210 Member

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    yeah im getting 0 faults atall, I only have vcds lite so can only do basic scanning.
    I put a few runs up a while ago and people said my injectors were maxed out 23ms i think, so i ultrasonically cleaned the injectors which slightly improved response and then i changed the fuel filter, the thing was 95% blocked and what a difference it made, but i think after 180k miles and a blocked fuel filter for most of them its time the pump was changed. im getting:
    bad mpg 24.7 average
    now and again when i start the car when its cold it will run rough at 500rpm for a few seconds
    when im giving it some and get to roughly 6krpms its as though there is a fuel cut
    This is gonna be hard to explain but i will try anyway: eg if i plant it at 2000rpm to the rev limiter it will hit this fuel cut, but say if i hold it at 3500rpm in 2nd for about for 10 seconds and boot it, there is no cut and the car really flies. Its as though the pressure in the system is lost by the time i get to the end of the rpms. I can understand how this might sound stupid but i just have a gut feeling its the pump, especially after how well it ran with the new fuel filter for a while.
    I thought mpg and fuel pump would be related because there wouldnt be enough pressure at the injectors to give it a really good mist?
    egt sensor could also be a culprit, i will change this too at some point, when you say air leak do you mean exhaust or intake? thanks
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  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Fuel pump sounds plausible after what you say... if its been trying to force fuel through a clogged filter etc then its going to lead to a premature failure...

    I have seen pumps fail a lot earlier than 180k so again plausible...

    24.7mpg is not that bad LOL... it is subjective to the types of trips you take and stuff... :)

    EGT probe will show as a fault when scanned... if no fault code then its fine and around 180 to replace so don't be too hasty... as for air leaks... any of the pipes under the inlet manifold are prone to split and cause vacuum/boost leaks...

    <tuffty/>
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  5. karl210
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    karl210 Member

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    ahh cool cheers mate, well it was a steady 29mpg before changing the fuel filter and when i changed that it dropped to 24 it must of been really blocking it, and spark plugs indicated it was very lean, there not too bad now but i think its only lean at the higher revs.
    Ive got rid of all those pointless pipes and fitted a catch can so no leaks there, also had new bosch maf, ful service, cts etc. Im chuffed i might have a car running all its potential power! lol cant wait!
    So back to the pumps, whats my best options on a budget? £90 intank one from ecp, inline etc? any advice would be great thanks
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  6. superkarl
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    superkarl MAN OF STEEL

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    post logs.
    you're jumping to conclusions here. pumps arent that cheap really.

    i live with 24mpg everyday, if you arent prepared to live with that buy a prius not a sports car.

    seriously tho, post logs so people get a good idea. multiple runs, 2k- redline, 3rd gear.
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  7. vfr800
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    vfr800 Member

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    Wish I got more than 22mpg ... mine is fine on proper roads or motorway runs but about town it's economy is poop.
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  8. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    Can you hear the pump priming when you turn the key? My pump went pop and wouldn't start the car, but leading up to it the pump priming sound got very loud!
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  9. Sam_
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    Sam_ Down under

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    Bloody K04 always on boost ...
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  10. karl210
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    karl210 Member

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    yeah i can hear the pump priming, if i start the car before letting it fully prime it will struggle to start, not sure if thats normal or not.
    Im happy to live with 24mpg thats why i have the car..... but im not happy with its performance for said sports car and the performance at the moment doesnt vouch for its low mpg, and the symptoms are leaning towards the pump.
    What logs are needed? and i can do some today i can only log upto block 21 though because i only have lite. cheers
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  11. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    IIRC 031 gives you AFR, which if it's lean at the top could indicate a tired pump..?

    If you do need to log 031 let me know and I can jump in and log it if you want? BTW saw the car outside the range last weekend, looks well!
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  12. karl210
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    karl210 Member

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    Cheers mate that would be a big help, if you wouldnt mind that would be great. Im free today all day/night so just let me know when is best for you. Thanks once i get it running right i can start making it look good, its crying out for better suspension and wheel spacers
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  13. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    Ok, I'm working until 5.30ish then need to get home and pick up the lappy and cable. Could meet you in the John Milne car park in Milnrow at about 6.30? could use the motorway slip road for logging...?
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  14. karl210
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    karl210 Member

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    yeah sounds like a plan mate, i'll see you there. thanks
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  15. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    NP, might be worth checking with the knowledgeable peeps on here about which three blocks are the key ones to log at the same time to indicate potential pump failures?
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  16. karl210
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    karl210 Member

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    anyone? what about other blocks which might be a good idea to log to see if there is anything else thats giving me these symptoms?
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  17. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    Ok, did some logging of Karl's motor on Monday. Here are the logs of the best two runs we could get in 3rd, WOT to red line (or as close as possible):

    [​IMG]

    [​IMG]

    The car only exhibited the problem that Karl's mentioned on one run (the on with the high CF's), it feels like hesitation at high rev's. No fault codes came up when we scanned it after the run. I'm no mechanic but it doesn't sound like the fuel pump to me, EGT's look fine, AFR looks ok (if not a little rich?). g/s is a little down given the spec of the car (large TIP, cone filter, stage 1 map), although that could be partly down to the non-aggressive stage 1 map and mileage of the engine.
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  18. karl210
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    karl210 Member

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    anyone with any opinions on my logs? we was stood still for a while with the engine running so there was a lot of heat soak if that makes any difference, cheers
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