1.4 Tdi Struggling to start..

I’ve had this on a JCB digger. Tried petrol in the tank to flush which helped but eventually had to power wash it, repeated the petrol flush and changed all the filters. Treated the new fuel with a proprietary anti bug treatment and it’s been fine since. No issues with injectors but even after all that cleaning the filters were dirty after 100 hrs.
 
George Hogg said:
I’ve had this on a JCB digger. Tried petrol in the tank to flush which helped but eventually had to power wash it, repeated the petrol flush and changed all the filters. Treated the new fuel with a proprietary anti bug treatment and it’s been fine since. No issues with injectors but even after all that cleaning the filters were dirty after 100 hrs.
Click to expand...
That's interesting George, can I ask what symptoms was the digger engine showing when you had this problem? Thanks, Dave
 
Becoming harder to start, instead of instant, then progressed to not starting over a period of a week or two. If you have any sign of black gunge then it needs a thorough clean.
 
@George Hogg is on the money.

Another suggestion for the list of possibilities.
Oil can get into the fuel and make it black and that's from a tandem pump internal seal failure.
Happened to me a couple of years after the bosch pump I rebuilt failed.
:)👍

Could it make the black film on top of the diesel in the tank? I don't know if engine oil sinks or floats or does a bit of both.

Their maybe a combination of faults causing poor start up and rough idle?
 
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Recap
@DaveySprocket car has done 175k

Jobs list

@DaveySprocket
  • Fuel filter ☑️
  • Glow plug relay ☑️
  • Battery
  • Fuel tank sender x2 ☑️
  • Headlight earth ☑️
  • Tandem pump
  • Injector loom
  • Drain plug screw☑️
  • Wiper mechanism
  • Crank position sender
@Little Dog
  • Cam position sensor
  • Injector loom
Injector seals
@TAABVW
  • Clear tube in diesel line (edited see below)
@audifan
  • Correct glow plugs
@Howey
  • Rev counter ☑️
@dj_efk
  • VCDS scan
@putyourmittenson
  • Injector seals & injector well wear
@Howey
  • Additional earth
@kp 115
  • Injector seals
@Chris Warren
  • Blobs of congealed diesel ☑️
@johnyfartbox
  • Non return valve☑️
@rotifer
  • Seals on fuel filter ☑️
  • Diesel radiator
  • Fuel pump internal/external seals
@George Hogg
  • Full fuel system decontamination

Sorry if I missed anyones input out of the list.
Let me know and I can add it in. :) 👍

Edit
Thank you @TAABVW for spotting my error. :)
 
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rotifer said:
@George Hogg is on the money.

Another suggestion for the list of possibilities.
Oil can get into the fuel and make it black and that's from a tandem pump seal failure.
Happened to me a couple of years after the bosch pump I rebuilt failed.
:)👍

Could it make the black film on top of the diesel in the tank? I don't know if engine oil sinks or floats or does a bit of both.

Their maybe a combination of faults causing poor start up and rough idle?
Click to expand...
Yes unfortunately I can't rule out more than one fault 🫣
 
rotifer said:
Recap
@DaveySprocket car has done 175k

Jobs list
  • Fuel filter ☑️
  • Glow plug relay ☑️
  • Battery
  • Fuel tank sender x2 ☑️
  • Headlight earth ☑️
  • Tandem pump
  • Injector loom
  • Drain plug screw☑️
  • Wiper mechanism
  • Crank position sender
@Little Dog
  • Cam position sensor
  • Injector loom
Injector seals
@TAABVW
  • Clear tube in diesel line☑️
@audifan
  • Correct glow plugs
@Howey
  • Rev counter ☑️
@dj_efk
  • VCDS scan
@putyourmittenson
  • Injector rmseaks & injector well wear
@Howey
  • Additional earth
@kp 115
  • Injector seals
@Chris Warren
  • Blobs of congealed diesel ☑️
@johnyfartbox
  • Non return valve☑️
@rotifer
  • Seals on fuel filter ☑️
  • Diesel radiator
  • Fuel pump internal/external seals

Sorry if I missed anyones input out of the list.
Let me know and I can add it in. :) 👍
Click to expand...
You're a star Andrew, I like you determination to keep me straight! :)
 
I note in list above we have a tick by the "clear tube in diesel line" but can't find anywhere in the thread where the clear tube has been used. I know I keep banging on about this but I see it as crucial to the fault diagnosis process. You are trying to establish whether air in the fuel is the culprit or not.

The clear tube needs to be inserted in the return fuel line. The aim here is to establish whether the tandem pump is bleeding air out of the fuel.
Start the car (preferably a dodgy start) and get an assistant to stare at the clear tube in the return fuel line for a few minutes for any signs of air bubbles.

I note the non return valve but the exercise above will rule out "air in" at the tandem pump fuel feed connection and the tandem pump gasket.

No air at all in the fuel return pipe after a dodgy start and I will shut up and eat my hat!
 
You don't need more suggestions.
But if I put myself in your position, what would I do next?

Low cost is pole
position as always.

The fuel filter drain plug seal.
Is the bolt you used fully threaded? May the thread have chewed the o-ring.
The OEM fuel water drain plug has a specific design so as not to damage the o- rings, not that I am suggesting you have. 😁
I would be interested to see what you used, can be the design you made be replicated off the car and if so would you post a photo of it please?

EDIT
Image credit @audifan
20240312_093031.png

20240312_093113.png
 
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TAABVW said:
I note in list above we have a tick by the "clear tube in diesel line" but can't find anywhere in the thread where the clear tube has been used. I know I keep banging on about this but I see it as crucial to the fault diagnosis process. You are trying to establish whether air in the fuel is the culprit or not.

The clear tube needs to be inserted in the return fuel line. The aim here is to establish whether the tandem pump is bleeding air out of the fuel.
Start the car (preferably a dodgy start) and get an assistant to stare at the clear tube in the return fuel line for a few minutes for any signs of air bubbles.

I note the non return valve but the exercise above will rule out "air in" at the tandem pump fuel feed connection and the tandem pump gasket.

No air at all in the fuel return pipe after a dodgy start and I will shut up and eat my hat!
Click to expand...
Yes you are of course entirely correct about this, and I did buy the clear pipe ages ago, but two things have been putting me off. One is that the fault is/was intermittent, and two is that I wasn't sure how to do it. But I will just have to man up and get on with it I guess, at least it will rule something in or out.

Thanks for the shove in the right direction
 
I think that I put the pipe on the incoming fuel line to test everything was sealed before the fuel pump. Then if that's clear of bubbles swap the lines to the return flow pipe and repeat. 😎👍

1.4 TDI parking down hill

Hello. I have had some problems getting the 1.4 TDI -04 to start and have searched the forum for some days, changing fuel filter, cleaning, checking hoses for leaks ( this one is hard but at least nothing leaks out, could still be sucking air) it worked fine during winter as long as it was...
www.a2oc.net www.a2oc.net

Edit

20240312_095624.jpg
 
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rotifer said:
You don't need may more suggestions. But if I put myself in your position, what would I do next?

Low cost is pole
position as always.

The fuel filter drain plug seal.
Is the bolt you used fully threaded? May the thread have chewed the o-ring.
The OEM fuel water drain plug has a specific design so as not to damage the o- rings, not that I am suggesting you have. 😁
I would be interested to see what you used, can be the design you made be replicated off the car and if so would you post a photo of it please?

EDIT
Image credit @audifan
View attachment 120527
View attachment 120529
Click to expand...
At the time I did it, it certainly seemed like a comprehensive solution, but is certainly worth revisiting just in case. I'm pretty sure I put and O ring in first, then a washer that fitted perfectly in the hole on top, then another o ring, another washer and the bolt, which probably was fully threaded.
As soon as my bundle of Fuel filters, and hose clamps arrive I will get in there again and see what is going on. Will also check the Blue one as I have not done anything with it. I maybe should just get on and buy the part that Depronman makes..

It is slightly bizarre, and also entirely wonderful how some folks who have never met, are willing to devote time and energy to resolving a random problem to help someone out and keep Audi A2's in service. All very heart warming, and much appreciated 😊
 
The intermittent nature of the poor starting might well point to air entering the fuel line; and also a bit of fuel restriction somewhere in the fuel feed.

So here is a theory and you can check whether it fits your symptoms:

Suppose you have a small "air in" leak somewhere near the fuel pump; and also some restriction in the fuel feed pipe (where ever that might be). Sometimes the small "air in" leak lets go and lets air in, sometimes it doesn't depending on: how much suction is present; how warm the ambient temperature is; how warm the engine is; how long to next start......
So for example, if the engine is hot at idle (low fuel demand therefor low fuel feed suction) and you switched it off and immediately on again, I might expect it to start reasonably well. The suction is low, rubbers warm and soft, not time for air to seep in.
However, If engine reasonably cold at the end of a short drive where fuel demand was relatively high. You switch it off and leave it for 5 minutes then try and restart, I might expect it not to start at all. High recent fuel load equals high suction in the fuel feed. Cold engine equals harder rubbers or contracted metals (tandem pump). Five minutes long enough for a 'nice' slug of air to be drawn through a small "air in" leak.

The clear pipe on the feed might give you some info but can be misleading as it will tell you nothing about the tandem pump. Since you have already tried a non return valve I would politely suggest this would be a waste of time. Clear pipe on the return is easier to do and will categorically rule out air in fuel or not. If the engine is running ANY air in the fuel from ANY source will be bled into the return fuel line, it has nowhere else to go.

The return fuel line in the engine bay is the lower of the two metal fuel lines going across the front of the engine. You could detach the rubber fuel hose from the left hand side of the lower steel fuel pipe (facing the engine). Plug the rubber tube with a bolt. Connect clear hose to metal pipe (possibly dip in boiling water to soften pipe end to fit over spigot), and feed into a bucket. Keep the clear tube going uphill to the fuel flow so you can see bubbles or not. I normally connect back up to complete the fuel system but it's not actually necessary if you are struggling with a reconnection method.
 
Thoughts on non return valves.

Dear @TAABVW I beg to differ.🙂


If its the valve is still in place remove it especially if it is near the tandem pump.

It's a false positive negative edit: for the test of air being in the line and doesn't help you diagnose that section of fuel line from the tank to the fuel filter and on into the tandem pump.
If you have an air leak before the one way valve it would be problematic not to know about it due to it being masked by the check valve.
A leak before the check valve will may reduce available air free diesel being fed to the fuel pump.

Edit
Another way of saying the above is....
a leak before the check valve that is introducing air to diesel fuel maybe masked by the check valve holding the fuel with less air in it upstream of the valve which could reduce cranking before the car starts)
It is important the whole system is airtight from start to finish. 😉👍
 
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rotifer said:
Thoughts on non return valves.

Dear @TAABVW i beg to differ.


If its the valve is still in place remove it especially if it is near the tandem pump.

It's a false positive and doesn't help you diagnose that section of fuel line from the tank to the fuel filter and on into the tandem pump.
If you have an air leak before the one way valve it would be problematic to not know about it because it's being masked by the check valve.
A leak before the check valve will reduce available air free diesel being fed to the fuel pump.
It is important the whole system is airtight from start to finish.
Click to expand...
I entirely agree with you. Leaving in a check valve in the fuel feed which might mask an "air in" problem in the fuel feed would be an entirely undesirable final solution. And yes I would remove the check valve since it adds more connections and potential for leaks. I was trying to explain why a clear pipe on the return would tell you ALL you need to know with respect to air in fuel or not, but a clear pipe on the feed would not.
 
The full explanation of all the possible causes was indeed correct and I agree that they are all plausible.

From a diagnostic point of view to check each section in turn and not introduce uncertainty in the findings would be how I would move forwards.
This forum for discussion is a great at collating data (ideas) from various sources.
The owner of the vehicle is free to choose what direction they take with their repairs which is the fun part.
:) 👍

Because there's usually photos to look at and they report back with what was done and if anything changed.
 
Did you managed to get full VCDS scan or just basic scan with generic scanner? Getting the VCDS scan done first could bring more light into the issue.
 
bix said:
Did you managed to get full VCDS scan or just basic scan with generic scanner? Getting the VCDS scan done first could bring more light into the issue.
Click to expand...
Basic but VW specific scanner shows no faults, I have non registered VCDS Lite, which I have not tried. I'm not sure if I have it register it to get any worthwhile results?
 
I would still try VCDS your lite is as good as normal it's just locked to one laptop. You need to register it trough the software. Your other scanner might not see all the codes and to be 100 % sure is to use good old VCDS
 
DaveySprocket said:
Basic but VW specific scanner shows no faults, I have non registered VCDS Lite, which I have not tried. I'm not sure if I have it register it to get any worthwhile results?
Click to expand...
The free, unregistered version will scan all controllers, you just have to do one at a time, as Auto Scan is only available to the registered version.
An engine scan will show all the engine fault codes, but will only add the description to the first code. This is not a problem, as you can Google the code, and find the description, or ask here.
The big restriction to the free version, is not having access to Measuring Blocks.
Get the scan asap, and go from there.
Mac.
 
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