Audi S3 8L - Door Open -> fuel pump prime

Interesting new twist to my problem.. My driveway is on a bit of a slope.

If I park my car with the front of my car higher than the rear, the car starts fine with no issues

If I park my car with the rear of my car higher than the front, the car starts and then splutters (sometimes stalls) then will run fine.

I'm thinking that it may be the regulator that's causing the problem as opposed to the fuel pump, as the level of my tank doesn't make a difference to the car starting.
 
Is it possible that the injectors are not closing fully causing it to leak fuel into the cylinders and flooding slightly?
Just a thought
 
Nah I don't think so, because the car starts fine for a second but then it's like there is air in the fuel line and it struggles to run. Doesn't seem like it's flooded where it would take a lot of cranking before it fires up
 
My FPR arrived, so just need to fit and see what happens...doesn't help that my battery is entirely flat lol
 
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That link you put isn't the thread I was talking about, but is similar, have tried looking for it but can't find it, was only last year not 2009, hope that your fpr helps though :)
 
I'm jealous you have your FPR already. Mine is still being flown around America :(
 
So, the mystery continues :(

I replaced my FPR, and I still have the same problem as before...if anything, it now might be more pronounced than before lol

So now, the car REALLY struggles to start - takes about 10 - 12 cranks to get it going, with all of them spluttering like mad. Even when going, it will idle at around 400rpm for a few seconds and then stall out. Once I finally get it going, idling at around 850 - 900rpm and holding itself, when I give it a little bit of a rev, it will rev and drop down to around 500rpm again, nearly cut out and then splutter its way back up to 900rpm idle...very odd.

Also, when it's spluttering away at around 400rpm, even the slightest bit of throttle just kills it.

So, any ideas?
 
If it's made the problem worse, are you sure the o rings on the FPR are okay?
 
To be honest I think the FPR was fine before. Taking the FPR out and looking at the o-rings, they looked fine - no damage. I replaced it anyway though, just in case.

Also, when I took the original FPR out, there appeared to be plenty of fuel left in the fuel rail (see picture) - so it's weird, because I thought this symptom was all to due with fuel starvation, but looking at the fuel left in the fuel rail after the car's been sat for ages, there's plenty there...or am I misunderstanding this?

So, any thoughts and help still welcome guys!!

Here is the fuel rail with plenty of fuel left after taking the original FPR out
Upload 2014 11 29 23 35 28


And the original FPR with fine looking o-rings
Upload 2014 11 29 23 36 47
 
The fact that it's made the problem worse seems weird though. Changing it has done something.. Put the old one back and see if it runs like it did before
 
Well, a new component can stress the actual problem if it didn't fix it. I'm keen to think about what else the problem could be, because it clearly isn't the FPR that is causing this (unless I have terrible luck with FPRs).

What about MAF?
 
Bumpy bump bump?

I guess my next task is looking at all the fuel vacuum stuff under the bonnet and seeing if there are any major leaks. Then I guess it's off to fuel pump town?
 
honestly if it's not the FPR I would put money on it being the fuel pump
 
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as would I...I'm just shocked that the new fuel pump that was put in could die again in only a couple months...Is the one-way valve in the fuel pump separate from the rest of the assembly?
 
the check valve is built into the pump. However, it could be that the pump isn't sitting correctly in the housing and the fuel is leaking past the o rings, or the fuel hoses aren't sealed on the fuel pump housing.

I still have a sneaking suspicion it could be the FPR, it shouldn't have made the problem worse. Maybe buy a fuel check valve that you can put by the fuel filter, and that would fix the problem if it was related to the pump
 
hmmm, could put another check valve in the way I suppose. But if the pump is installed incorrectly, I should really fix that too.

Anyone know the specs of the check valve I would need to buy? (flow rate / pressure / diameter etc)?
 
My new pump improved the original issue but when the tank is low & the car sits the problem re-occurs. I defo noticed an improvement after installing the new pump though just this particular issue has re-occurred
 
As far as I know (I'm no expert) it could be one of three things.

1) Fuel going back out of the fuel rail the way it came (would indicate fuel pump issue)

2) Fuel going back out of the fuel rail through the fuel return line (I think this would indicate a FPR issue?)

3) Fuel leaking out of the fuel rail (Might be leaking out of the injector seal?)

As I said, I'm no expert and could be completely wrong, but with my basic knowledge that appears to me the only three causes
 
what's confusing me in my situation is that I took my FPR out, and the fuel rail still had fuel in it...
 
Was this after the car had been sitting overnight? Maybe it's the injectors?
 
yes, had been sitting over a week, and still had fuel in the rail when I popped the FPR out
 
Changed my FPR on the weekend and there was still fuel in the rail. When the car is parked flat it starts okay. But I had it on my driveway and I decided to just turn the key as fast as I could to not let the pump prime and it had it turn over a lot before it started. So I'm going to change the injector o rings (really doubt that will help) and then it looks like the fuel pumps coming back out :(
 
I have read somewhere that this could also be linked to the fuel pump relay... not tried it personally and I think the relay is a little pricey so worth have a quick research on this angle to see if its a potential cure...

<tuffty/>
 
Thanks for the tip Paul, I'll have a search of the forum tonight regarding relays.

If you had any other suggestions as to what it could be that would be great!

Otherwise I'll buy a new fuel pump + housing and save my aftermarket pump for when I go hybrid and worry about it then...
 
okay so I've fitted my new FPR and it hasn't fixed my problem either. I just brimmed the tank so I will see if it starts fine in the morning with a full tank. If it does that would narrow down the issue to either the fuel return like or something in the fuel tank (ie pump or the pump housing) I think....?

If anyone has any ideas it would be greatly appreciated.. I've ordered new injector O rings for the heck of it.

Squirrelofdoom said:
I'm thinking my next step is fitting a check valve after the filter
Click to expand...

Do you have this starting issue with a full tank?
 
I don't think it's fuel related (hope it is), i had a similar issue a long time ago and it was a cracked head. The cracked head was letting moisture onto the plugs which made the car splutter on the first start, eventually it got to the point it needed a few cranks to get in going.

Check for exhaust gases in the expansion tank or do what i did, put some red food colouring in the expansion tank, go for a drive then pull each plug out one by one, when you find the plug that's turned pink, you've found which chamber has the issue/crack

....hopefully it's not this but sounds very much like what i went through
 
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I'm still at the point of thinking fuel for mine. Mine cranks without even a hint of a splutter for lots and lots of attempts until it then begins to splutter and then gets better and better until it eventually fires...so I'm still leaning towards fuel retreating to the tank.

Also, the heads are pretty reliable on these cars, so I would be surprised to see this many of us all suffering from cracked heads at the same time :)
 
Mines AMK, currently in with Bill getting some work done. The compression was down on all cylinders by ~20psi except cylinder 2 which was down by ~40psi. Cylinder 2 also showed a 60% leak on the leak down test. It's having new stem seals, guides and the valves relapped I think. However, it's also having a new fuel pump whilst its in. Anyway, why would a cracked head only make it hard to start the car with less than a 1/4 tank of fuel?
 
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Alex C said:
. Anyway, why would a cracked head only make it hard to start the car with less than a 1/4 tank of fuel?
Click to expand...
I think Sandip was suggesting the plugs were getting wet with coolant. And/or cylinders would be wet when left, making it difficult to start
Sandip said:
The cracked head was letting moisture onto the plugs which made the car splutter on the first start,
Click to expand...
 
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