S3 Wont start basics!

mephisto

mephisto

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Ok my new S3 8l isnt happy. Was ticking over fine before i bought it.

Got it home had a dead battery, put a new battery in, took a good 5-6 seconds of turning over before it fired into life. Pulled out of driveway down road ev time i accelerated massive flat spot. Then it died. Turning over nothing. Started again for 5seconds. Dead again.

My gut feeling is fuel supply either contaminated or fuel pump, its been SoRNd for a 10months although it really was running fine on tickover for a good 10mins few days back.

I have an OBD eleven not tested yet but i guess i can get fuel pressure readings? Any checks i should make most appreciated.
 
When it died, did the dashboard light up or dim in any way? Have you considered the alternator? I think they can go all of a sudden.

Fingers crossed.
 
Hmm not.considered alternator no. This is a brand new battery fully charged.
 
You can't get fuel pressure readings from an OBD tester there is no fuel pressure sensor. Did you ask why it was SORN for 10 months.
I would have a look at the fuel filter and make sure it's been changed. They don''t get changed as it's not a service item.
Fuel pumps for these are not that cheap, not for a decent one anyway.
 
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Crank sensor is another possibility... Scan for codes as a start rather than guess or assume though

<tuffty/>
 
Thanks for tips so far. Will check for faults and fuel filter. May grab one from euro on way home just as precaution.
As much as this is a pia I need to get to know the engine more good way to start!
 
usual suspects, fuel or spark dude..
remove plugs... wet or dry..?
can you hear the pump and fuel prime on cranking?

etc etc
 
Thanks Bud, funny because when i was checking before buying i noticed some weird sound from the back of the car, like a fluctuating buzz thought it was the exhaust resonating..could of been fuel pump in hindsight (it did cross my mind)! Gonna check fuel pump first i swear it's fuel supply. I have a spare S3 i can compare with. Thanks all so far.
 
when I had a vacuum leak under the cross support near the brake master cylinder the car kept cutting out, not starting etc

Leak
 
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Tried starting again this morning, no noises at all from rear sounds to me like Fuel pump kaput as it's very quiet with ignition on. Going to pull it out in morning and test it. Looks pretty easy to get to.
 
Scanned it for fault codes yet?

Not seen a pump totally fail as yet but have seen one go weak on the dyno on a std map so that would have been pretty close to total failure...

Logging in VCDS would also give an indication as to if the fuel pump is on its way out... getting fairly common now for S3 pumps to fail

<tuffty/>
 
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mephisto said:
Tried starting again this morning, no noises at all from rear sounds to me like Fuel pump kaput as it's very quiet with ignition on. Going to pull it out in morning and test it. Looks pretty easy to get to.
Click to expand...

You will only hear the fuel pump for a few seconds to prime the system I don't think it just buzzes without the engine running.

Would it be easier to check the fuel rail or FPR?
 
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<tuffty/> said:
Scanned it for fault codes yet?

Not seen a pump totally fail as yet but have seen one go weak on the dyno on a std map so that would have been pretty close to total failure...

Logging in VCDS would also give an indication as to if the fuel pump is on its way out... getting fairly common now for S3 pumps to fail

<tuffty/>
Click to expand...

Ok i have OBDeleven pro (not that i am yet ;) can i see it in there i wonder?
 
Stuart B said:
You will only hear the fuel pump for a few seconds to prime the system I don't think it just buzzes without the engine running.

Would it be easier to check the fuel rail or FPR?
Click to expand...
Ok sun is shining going to go out and try and find out why she no start. Where's a good place start to check fuel pressure what do loosen on fuel rail to see I have fuel? I'm used to my 8p s3 no fuel pump visible to me! Thanks

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Can't you just pull the circlip off the fpr and prise it up to see if there's any fuel below?
 
I take it you mean this one... it doesn't want to pull out or shouldn't it. No fuel leaking when cranking engine
5ebe37644153f0522e94202443b12259.jpg


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No fuel comes out of this one when cranking is this fuel return?
ec685fd00a709de6d11516b520dd4a42.jpg


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Yes the FPR will come up I assume you still have the clip which was locking it down. You need to gently prise it up, you won't damage the o -ring with a screwdriver as it is only about 1cm wide in the middle, but you will bend the metal bracket where the clip goes if not careful, Stick a screwdriver in the slots where the clip was and ease it up from the edges.

You can also read it up levering from under the vacuum. Remember it is both old and sucking itself down, careful a load of grit doesn't drop in.
 
Ok prized It off ignition on turning engine no fuel coming out..the top?

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Sorrry supposed to attach pic.. No fuel overflowing when turning engine...
d3f06a20d9ace270682629a9bf556dc6.jpg


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I don't know if it is supposed to be spurting out, the fact there is fuel there means there is fuel in the "fuel rail", isn't that enough to fire up the engine? when I changed my fuel filter it took about 40 seconds of turning over until I got fuel there to start. I don't know I'm afraid.
 
Well i expected fuel to **** out when i turned on ignition as its fuel injection must need some good pressure, i thought that widget i took the top off was pressure regulator. Thanks for your help all the same, ill have another go at this later.
 
It should fly out. Should be under some pressure too. Many a time I’ve taken a FPR or injector off and it’s ****** everywhere.
Check fuse for fuel pump and the relay etc
Can you hear the pump at all upon turning the key?
 
Thanks SuperKarl for confirming my assumptions. ok will check fuse first i guess. However the behavior down the road beforehand of flat spots and then stall let me to believe pump failing or some blockage occurring.. im gonna check and compare turning key as i am fortunate to have my friends S3 8L here to compare. Will report my results.
 
It only takes a couple of hours to change a fuel pump, might be worth doing in any case.
 
Arghh it's fixed!?

Now for anyone reading this my fault finding.

1. Remove circlip and prize off fuel pressure reg. Crank engine only when ignition is cranking will fuel pump activate check for fuel flow.

2. Check fuse for fuel pump.

3. Lift off back seat left hand offside black disc 3 screws remove.
Try starting car you should be able to hear and feel fuel pump working.

4. Remove right hand pipe nearest front of car from fuel filter. Crank engine check for fuel pressure. Refit pipe quick to prevent excessive fuel leak.

5. Replace fuel filter if in doubt. Drop hand brake cable down, 7mm socket undo jubilee clip drop filter. Pinch gently and twist away connectors. Note fuel flow direction on filter matches when you refit.

6. Make sure your fuel indicator isn't telling you porkies add a litre or two of fuel just incase you have run out of fuel.

I followed all 6 steps here. Then DOH I had still left the pressure reg off under bonnet yes I know..
So I'm still not sure if it was a blocked fuel filter or I had just ran out of fuel even though needle shows edge of red and 45mile range?!

Thabkyou to all that helped here.. and hope above helps someone else.
Ĺ
0806ba872cab85f018bf761086d2d32c.jpg


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The fuel tank in these has essentially two halves and two sensors to measure the level in them. There is a suction jet arrangement that pulls fuel from the one tank into the other . If the pump isn't working correctly for some reason it doesn't pull all the fuel from the one side of the tank. The car can measure this fuel but you won't be able to use it. This may be what your problem is and you actually ran out of fuel.
No harm changing the fuel filter, they are cheap enough but are never changed. On my 15 year old 90k TT it was still on the original.
 
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Well done for fixing it, maybe the fuel level arm got jammed, if you fill it up it might help reset it.
 
audi upgrades
desertstorm said:
The fuel tank in these has essentially two halves and two sensors to measure the level in them. There is a suction jet arrangement that pulls fuel from the one tank into the other . If the pump isn't working correctly for some reason it doesn't pull all the fuel from the one side of the tank. The car can measure this fuel but you won't be able to use it. This may be what your problem is and you actually ran out of fuel.
No harm changing the fuel filter, they are cheap enough but are never changed. On my 15 year old 90k TT it was still on the original.
Click to expand...

Argh this rings true for two reasons:

When i felt the pump it just sounded hollow and high revving like it wasn't picking up fuel.
I blew into the input of the old fuel filter and fuel shot out exit, seemed to be not blocked at all.

Saying the all the diagrams i see of the pump there is a single float and suction unit i dont see how it sucks from one side.. do you have a diagram to illustrate?
 
http://www.volkspage.net/technik/ssp/ssp/SSP_207.pdf Page 46
This is for the TT but it's the same on the S3, The fuel pump on the Quattro cars is different to the fwd cars as it has an outlet on the top that pumps fuel over to the suction jet pump on the other side of the tank. The suction jet then passes fuel back to the main tank with the pump in.
This way fuel levels should be similar in both sides of the tank.
If there is a problem with the suction jet or the hoses aren't connected properly then then fuel will remain in the one tank when the level is low.
I think it's possible to fit a fwd pump to a Quattro car but then you won't get the suction jet pump to work.

http://www.ttforum.co.uk/forum/viewtopic.php?t=552313
 
Thanks so much desertstorm for these two articles, exactly what ive been looking for to better understand the Fuel system fantastic.
 
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