HELP! W reg A4 2.5 TDi cranks but won't start

[timthetinyhorse]

Hi,

My B5 A4 2.5TDi has developed an issue where it turns over for ages with lots of white smoke before it eventually fires but yesterday it point blank would not start, it turns over strong and puffs out white smoke which I believe to be unburnt fuel, the rac came out and it fired on the first squirt of easy start......any ideas?
I read somewhere about air bubbles on the clear fuel line, I have had a look and mine had one small bubble in the line at the filter end but that's all.

The only thing that exaggerated the issue was that I topped the oil up last week, I have double checked it's not overfilled and it's dead on the max line. It's got me baffled as it runs perfect once it's going and the engine temps are perfect!

Any info would be great!

Cheers

[imagineifyeswill]

Once youve got it started from cold does it start allright the rest of the day or is it hard to start every time. A disel which is difficult to start in the morning from cold but ok for the rest of the day could have a head gasket just starting to fail.

[Jimmyarm]

It needs to be looked at by someone with some diagnostic equipment (i.e. Vagcom).

What you are describing suggests several injectors have failed open but without looking at the cranking rail pressure etc it's impossible to say.

The fact that it starts easily on easy start is good, it pretty much rules out compression issues (although this should be checked as a matter of course with non start issues, if one of the injectors has been fooked for a while it can cause engine damage)

Basically, someone that knows what they are doing needs to investigate it !

[timthetinyhorse]

Thanks for the input guys,

I'm pretty sure that it's a fuel issue so I'm sorta happy it's not terminal, I was terrified it may be the HG on one of the banks but the coolant temp has been stable through everything.

I hadn't considered the injectors being stuck open so that's a good avenue and I was worried it was the ultra expensive fuel pump but that would mean no fuel but it looks like I'm getting too much fuel or fuel at the wrong time so hoping to rule that out too.

The one big possibility (from forum trawling which I know isn't the best idea) is that the timing belt has skipped a tooth on the pump gear and the fuel timing is out however this would not explain why the problem has got gradually worse and not happened suddenly.

Litteraly 1sec of easy start is easy enough to fire her up so I think it could be a relitively simple problem but as I have never had to work on a disel before it's with my trusted mechanic.

Wish me luck!!

[timthetinyhorse]

Just spoken to mechanic who had a vag expert look at it and he suspects the advance piston on the disel pump is stuck open.....going to plug it in on Tuesday to make sure but I'm now scared it's time to scrap the car!!