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Billy, Trainer/ Master Technician
Category: Audi
Satisfied Customers: 3498
Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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I have a 2006 audi S4 and there is no power to the fuel pump

Customer Question

Hi, I have a 2006 audi S4 and there is no power to the fuel pump fuse looks good and so does the relay if I tested the right one any ideas would be much appreciated thanks
Submitted: 2 years ago.
Category: Audi
Expert:  Billy replied 2 years ago.
Hello and Welcome! I'm Billy and i will assist you with your inquiry. Feel free to ask if any further info is needed.
My apologies for the delay, thank you for your patience.
When trying to start do you get spark?
did you check for any fault codes?
Customer: replied 2 years ago.
hi Billy, I did not check the spark because the fuel pump does not come on I replaced it with same results. I did check for faulty codes does not show any. thank you Pat
Customer: replied 2 years ago.
PS; I also checked fuse and replaced relay
Expert:  Billy replied 2 years ago.
Hello Pat,
There is relation between spark and fuel pump:
- if the engine control module doesn't detect good cam and crank signal, you will get no spark and no fuel pump activation. So we will have a direction of diagnosis to know what to check next.
Another thing you could do, would be powering the pump directly (12v supply), and see if engine runs.
- also another thing, would be spraying some easy start fluid in to the intake while trying to start.
Kindly get back to me with your findings, so we proceed as needed.
Customer: replied 2 years ago.
hello Billy, Pat again I tried the started fluid idea and you were right not a pop
Expert:  Billy replied 2 years ago.
Hello Pat,
Are you able to check using a scan tool for camshaft and crankshaft sensor signals while trying to start?
as if any of these is faulty, it would cause this.
And did this problem start suddenly? is the engine cranking at normal speed? or does it feel faster or even slower than usual?
did you check for any blown fuses?
did you try starting using another key (if available)?
Customer: replied 2 years ago.
I only have an OBD2 scanner and I'm not sure if it will read the camshaft or crankshaft sensors.
The problem started out where the car would start fine when cold, but after driving for 10 minutes or so it wouldn't want to start after that. So we replaced the pump thinking it was the pump. But obviously it is something beyond the pump.
All of the fuses look good. Also tried starting the car with another key, no luck.
Thank you.
Expert:  Billy replied 2 years ago.
Hello Pat,
In this case the next step would checking the camshaft and crankshaft signals. Try to look them up in the scan tool, and try looking for rpm signal as well... Get back to me with your findings, so we proceed as needed.
PS: most obdII tools do include cam and crank signals.