S3 Fuel System Chaos: Rough Starts and Stalling Woes

Had similar symptoms on a 2015 RS3 last month. The rough running and engine stalling turned out to be more than a basic fuel pump failure. Auto repair revealed multiple issues in the fuel system, including corroded electrical connections at the fuel pump assembly and a failing fuel pressure regulator. The key symptoms matched exactly: hard starting, rough idle, increased fuel consumption, and engine stalling. Initial diagnosis pointed to the fuel pump, but further inspection showed the wiring harness connectors had degraded, causing intermittent power supply to the pump. This was a serious repair job requiring removal of the fuel tank for proper access. A complete fuel system inspection revealed the full scope of the problem. The car mechanics found that moisture had penetrated the electrical connections, leading to corrosion and unreliable pump operation. While a straightforward pump replacement might temporarily fix similar issues, proper diagnosis of the entire fuel system is crucial. The complete repair should include checking electrical connections, fuel pressure, and system diagnostics to prevent recurring problems.

Thanks for the detailed response about your RS3 fuel system problems. Your symptoms match mine perfectly, especially the engine stalling and rough idle issues. Really helpful to know about those corroded connections, will definitely have that checked when I take it in for automotive diagnosis. Quick question, can you remember roughly what you paid for the complete fuel pump repair? Also wondering if youve had any other fuel system problems since getting it fixed?

Actually, the repair turned out much simpler and cheaper than expected. The fuel pump itself wasnt defective, it was just a faulty cable connection causing intermittent power issues to the pump. Once the car mechanics identified this during automotive diagnosis, fixing the connection cost only 95 Euro. Since the repair, the fuel system has performed flawlessly. No more engine stalling, rough idle is completely gone, and fuel consumption returned to normal. The check engine light hasnt come back either. This highlights how important proper diagnosis is, what seems like a major fuel pump issue can sometimes be a straightforward electrical fix. Running smooth for over a month now with zero fuel system problems. Going straight to the electrical connections saved a lot of money compared to unnecessarily replacing the entire fuel pump assembly. Good luck with your S3, sounds like it might be facing similar issues.

Just got back from the mechanic and wanted to update everyone. You were right about checking the electrical connections first. The car mechanics found corroded wiring near the fuel pump that was causing all those starting and stalling issues. Total repair came to 120 Euro for cleaning connections and replacing some damaged wiring. No need for a complete fuel pump replacement after all. The engine starts perfectly now, idle is smooth, and fuel consumption is back to normal. Really glad I asked here first. Would have probably agreed to an unnecessary fuel pump replacement if I hadnt known about checking the electrical system. The whole repair took about 2 hours and saved me from a much bigger bill. Thanks for helping me avoid another bad repair experience. Will definitely keep an eye on those fuel system connections going forward.