A4 B5 2.5TDI AFB Wont start when parked on a hill ??

[elefant_man]

Hi I am new to the forum so Hello

I have a AFB 2.5TDI Man 6 speed.

The car has an intermittant starting problem.

Most of the time the car fires up straight away no problem but every 2 or 3 weeks it takes 30-40 seconds of cranking to get it to start. It is normally parked on the flat day in a day out. Every time the car is parked nose up on a hill it refuses to start and I have to push/tow the car onto the flat level.. Once on the flat the car will start up after 30-40 seconds of cranking. Today I went out in the car parked it outside started it back up pulled it on my sloped drive washed the car (took about 30 min) and it refused to start I had to put it back on the road (flat) and after 40 seconds or so it fired up no problems

I have checked around for visual signs of leaks as it appears to be that the diesel is draining back to the tank there are air bubbles in the clear plastic fuel pipe that runs to the injector pump. I have replaced the return pipes on the injectors as these were worn. The car had a new fuel pump fitted by Audi last year and has full history runs and pulls well.

I have Vagcom and this shows no faults on the car.

Has any one got any ideas as to the root of this problem.

Thanks

[avanttdi]

Disconnect the supply to the fuel injection pump, and stick it into a very clean container of diesel. bleed it up and start it. park it on a slope. leave it and see if it still does it.

if its ok, then you have a dodgy fuel line somewhere.

if the problem still occurs, then the fualt is elsewhere. Among other things, are you sure its just not a coincidence that you happen to park it on a slope when the fault happens??

AvantTdi

[elefant_man]

I will try rigging it up to another fuel source and see what happens. It is def not a coincidence as it does not start every time I park it on the drive. The car has done this for the last 16000 miles over the last 6 months and it has not got any worse.

Thanks

[YORKIE]

Hi, i got the same car and had the exact same problem after rebuilding the top end of the engine. At first i thought it was because the fuel was low (not empty) in the tank, not that this time. i cracked off the RH injectors and it fired up fine ran ok for two weeks the parked on same hill. 1 hour later it refused to start. i spoke to a local specialist and he advised me to fit a new filter (GENUINE VAG PART), i was sceptical as i had put a new one (AFTERMARKET) on two weeks previous. Did what he said, bled it again and it fired up fine, 2 years later and never had the same problem. (and yes i still park on the same hill, nose up.

[elefant_man]

Thanks for that I will change the filter out for a genuine VAG. It did it befor I changed the filter for a non VAG part but no idea if it had a genuine one in before or not. So for the price of a genuine filter I will just change it anyway.

Thanks

[squiz]

hi i had the same problem a few years ago, when parked on a hill the sediment that collects in the bottom of the filter used to block the outlet if parked on a hill, guess it hadnt been changed in a long time ! All fine after filter swap !!!

[DaM Designs]

I had the same problem with my 325 tds, it was caused by a poor fuel filter allowing the fuel to drain away to the tank when parked on a slope. My local specialist put a Non Return Valve in the fuel line to stop any chance of it happening again, if a garage should put a aftermarket filter on in the future. Maybe a solution for your tdi ?

[All-rod]

I had the same problem with my 325 tds, it was caused by a poor fuel filter allowing the fuel to drain away to the tank when parked on a slope. My local specialist put a Non Return Valve in the fuel line to stop any chance of it happening again, if a garage should put a aftermarket filter on in the future. Maybe a solution for your tdi ?

Hi, this is very common problem with filter, most of the time fuel runs back to tank, but sometimes O-ring in return valve for fuel preheater at top of filter fails and lets air in. Now what sort of non return valve shold we be looking for, can anyone recommend which one to buy and where?

[DaM Designs]

Sorry, couldnt give you any exact details with ref' the valve but it is a VERY common problem so any BMW specialist would be able to tell you straight offand also as to whether the diameters of the valve and Audi fuel lines are compatible.