kishjancsi

My wife's A6 2.7T with 100k miles wont start for the first time after like 10 hours standing, but starts fine otherwise. Can someone please help?
Thanks,
John

SloopJohnB@mac.com

In the old days this would often be a loss of fuel injection line pressure due to a failed checkvalve in the in-tank fuel pump.

In this case, you probably need to give a little more information, like does it start after 10 seconds of cranking rather than the normal 1-2 seconds and va-room!

4Driver4

Any codes? How old is the coolant temp sensor? That would be my first guess given the limited info.

5v/cyl

+1 Typical coolant temp sensor problem.

kishjancsi

Thanks gents for the replies
It starts right away after the first cranking
I'll try to get some codes

5v/cyl

May not show a code b/c the ECU doesn't know it is bad. A VAG-COM will be able to show if it is bad. Easiest check is to see what color yours is. Green is probably good. Black is bad and needs to be replaced with green.

Most likely the sensor is stuck in the hot position so when you go to start the cold engine the ECU thinks it's already hot and isn't shooting extra fuel in, so no start. With the 2nd crank the fuel has built up in the cylinders enough to fire and all is good till it cools off again.

RacerX72

Hello All, I have this problem with my 2001 A4 1.8t, it won't start in the morning the first time usualy starts the second time sometimes third...when the car is warm starts perfectly, its usualy when it has been sitting for few hours. The fuel pump is brand new and the pressure regulator is working good. I recently replaced the Temp/Coolant sensor...I think it has to do with fuel pressure loss, WHAT ELSE COULD IT BE?