Rs6 cold start issues

[mbagge01]

I have noted for the past couple weeks that are cold starts, it now takes two turns of the key to get the car started. On the first turn, it starts but then dies, but are always starts and keeps running on second turn. Can has no driving issues when finally running. Could this be a sign of the primary or secondary fuel pump started to fail. I check the vacuum seal on the FPR to make sure if was not leaking on loosing pressure when car off. I get the feeling that when the car is off for a while the fuel pressure does not build up enough to turn car over on cold start with first turn.

[ShelbyM3]

That would be my suspicion, too. I have a similar problem on an 02 Allroad. I believe there’s an internal check valve that maintains pressure at the fuel pump and if this fails you essentially are building pressure each start. And, if I’m not mistaken, your fuel pump won’t prime until you crank, so giving it time to prime does nothing. This is what I’ve convinced myself, at least.
A thought I’ve had is to jump the fuel pump relay to try to prime the system for 10-15 seconds before a cold start and see if that makes a difference. Could be worth a shot. I have also heard of fuel pressure regulators failing, but I’d lean toward fuel pump before the regulator.


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[Avantly]

I've had similar issues on C5 before (not RS6 though) and in all cases it was either the fuel pump, or a leaky injector that was bleeding fuel pressure down after the vehicle was off for a while. I've also had starting issues from ECT's which have severe offset in temperature reading but those usually cause a serious problem with warm/hot starting before they can cause any issues with cold starts.