Hard to start and slight hesitation

[A3Quattro]

OK, I have a 2007 A3 Quattro. It has FSH and has just been serviced at 88000 miles. When I go to start the car in the morning if I just turn the key without touching the accelerator peddle the car will often fire and stop or fire and run really rough for a few seconds. Once the car has been started you can then restart just using the key no problem. Along side this there is an annoying hesitation at low RPM (1-1.5k). It feels like a fuel starvation problem. I have checked the fuel filter and it has defiantly been changed on the service. Something is wrong and I don't know what to do. I have Vagcom but unsure what to check for help..... PLEASE HELP, it's driving me mad.......

[A3Quattro]

Well I'm gutted no one can help. My issue seems to be slightly worse now.... When the car is left for a few days and I try to start it the engine spins over and nothing happens. I have to keep on turning the engine over, pumping the accelerator, almost untill the battery dies!!!

I have Vag-Com but unfortunatly no idea what to log. I am thinking it's a fuel supply problem as even the next day I have to put my foot on the accelerator to aid starting, otherwise it can take a real long (over 10 seconds) crank to get going!!!!

PLEASE PLEASE HELP........

[Guest 2]

As you said you have vagcom, connect it and switch on the ignition and start a fault code scan and post the results if anything appears then post it up here.

[A3Quattro]

Hi Chris, thanks for your reply. The first thing I did was to check for faults using vagcom. Nothing to report there though. Everything is showing with no errors.
I am hoping someone will tell me to monitor certain blocks in vagcom to check fuel pressures etc.

Fingers crossed.

[sy.]

is your car petrol or diesel?? and is the car sometimes lumpy on idle??

[A3Quattro]

Hi, sorry, I forgot to mention my car is diesel. It's slightly lumpy on tickover if it has been hard to start. Once you have revved her slightly the tick over is Ok. Can it be some fuel pressure that drops over time? I'm not sure hoe the fuel system works on this type of car!

[a8 tech]

insufficient cranking rpm caused by weak battery or worn starter motor

insufficient residual fuel pressure caused by leak off or defective tandem pump

excess soot in fuel caused by blow pass at the injectors

incorrect fuel or coolant reading

pre supply pump in the tank defective or air being drawn in

[A3Quattro]

Crikey!! Thanks a8 tech.

I am drawn towards the residual fuel pressure or pre supply pump due to the fact it gets worse the longer the car is not used.
Can you give me any guidance on how to check for problems with these two units?

Sorry for all the questions. I've had enough experiance with buying expensive parts already....

Many thanks.

[a8 tech]

try to fit a clear fuel pipe from the fuel filter to the tandem pump in port and observe the fuel flow when cranking

or clamp the return hose the evening before then see if it starts better

for slow cranking boost start it and see if it makes any difference

try these basic tests before waving a multimeter at it