Hey everyone, I have a problem with my 2004 Audi S4. It is auto with 70k on it. My problem is it gives me a hard start when turning on. The car cranks and cranks for several seconds before it actually starts. This appears to only happen after it sits for more then an hour or so. If I start it, shut it down, then start it up right away it starts in like 2 cranks. But once its sits for some time it will hard start again. Most of the time I let it crank for a while, stop, then crank it again and it will finally turn over.

So far I have replaced the spark plugs, battery, fuel filter, and even tried the spare key – non of which solved the issue. Does anyone have any suggestions or had a similar problem? I have searched around and couldn’t find any similar treads.

Thanks for your help.

 

First i would do a simple compression test to make sure the engine is not at fault....

... but kinda sounds like a fuel pump issue if spark plugs didn't help(assuming you used OEM parts or better)

 

I did use OEM parts from Audi.

I always suspected it was fuel related but wanted some other opinions. Is there a way to measure fuel pressure on the S4s? I was told by a mechanic that there isn't. Would the fuel pump be the common culprit or the fuel pressure regulator?

 

i havn't had any fueling problems with my s4 nor hear of any fueling issues with these cars yet.... how about buy a fuel pressure gauge and tap it into your fuel return line and see if the fuel pump is keeping pressure at a normal level...

 

I have heard of the 4.2s cylinder walls wearing... I vote comp test

 

Hey everyone…I know its been a while but I have finally fixed my hard starting problem. Turned out to be the Fuel Pump. As a reference for anyone in the future its part number is W0133-1762816-OES and I found it the cheapest through Amazon for $348 shipped. The dealer listed it for around $450. The installation was pretty straight forward – I used this write up as a reference http://www.a4mods.com/index.php?page.../fuelpump.html. Thanks all for your help.

 

bringing this back from the dead but was searching for a solution to my problem on my 3.0 a4. sounds like i have almost the exact same symptoms and was wondering how you figured out it was the fuel pump?