High pressure fuel pump replacement
While mine is the first instance of this being a problem that I’ve seen reported, it was apparently not an unknown problem to Audi, as they have improved these fuel pumps recently.
The problem:
Very suddenly, my S6 lost the ability to rev over about 4k rpm. Any throttle input beyond about 20% actually resulted in the car slowing down! It was as if the engine was being suffocated. Turns out, that’s exactly what it was. The problem was accompanied by a solid-lit EPC light on the dash, which turned off after a while, until taking the RPM’s close to 4k again, when it would light back up. The Engine light would also illuminate solid occasionally, though not always at the same time as the EPC light, and also turned off after a while of driving the car gently.
The Diagnosis:
I took the car to my local German auto shop, and they quickly were able to determine that the fuel pressure at the high-pressure pumps (located as pictured below) were not functioning at all, the only fuel delivery was coming from the main pump in the gas tank. This problem is sometimes accompanied by (or the result of) bad camshaft chain followers, but we inspected mine and they were fine. Audi’s official recommendation is to replace both high-pressure pumps at the same time, even if only one of them is bad.
The solution:
The original Audi part number for this is 07L127026A. This has been replaced by a new part number, 07L127026AD. The MSRP is $490 each, however I found them online for $330 each, plus an insane shipping cost of $70 for Fedex Ground, but still almost $200 cheaper than MSRP for the pair. The new pump includes everything you need, so you won’t need to buy anything additional for this project, as long as you have torx bits and metric wrenches.
Once you’ve got your new fuel pumps, locate the existing ones. Here’s where to find the High-Pressure fuel pumps: (could it get any easier??)
http://i.imgur.com/BXdmZHe.jpg
And here’s what a new fuel pump looks like, straight out of the box:
http://i.imgur.com/f5QdrWU.jpg
The process is really simple. First, disconnect the wiring harness from the old fuel pumps (you’ll need something to poke the plastic tab, like a small flathead screwdriver). Then, make sure the engine isn’t piping hot, because you WILL spill some gasoline on top of it! Expect 1 or 2 tablespoons of gasoline to spill. Next, unscrew to fuel line nuts all the way using a wrench (you’ll need 2 different size metric wrenches, forget which sizes at the moment), and gently pull the fuel lines away from the pump if you can, if you can’t move them much don’t stress about it. Next, you will need to recover the old torx bolt/washer from the side of the old fuel pumps, to install into the new fuel pumps where the little black rubber protector is plugging. It’s in there REALLY tight, so it’s easiest to do this while the pumps are still mounted to the engine, otherwise you’ll probably need to use a vice. Finally, remove the 3 torx bolts for the fuel pump (and don’t lose them!), and pull the old pump out of the engine. Install the new pump in the opposite order, using your old bolts. Last, install the smaller torx bolts your removed from the old pumps, and tighten them hard to make sure they won’t leak. Plug in the wiring harnesses. Make sure all gasoline is cleaned up, and let the car sit for a little while to make sure any other gasoline has evaporated.
Start the car with the hood open, give the throttle a few revs, and check for leaks. If not leaking, you’re done!
