tcwippy65

I've searched all over these forums and found a bunch of info about the high pressure fuel pump for the TDI, and videos for the A4 2.0's, but nothing about the 3.6L engine in my 2009 Q7 (91k miles). My car is performing poorly, lack of power, surging, etc, and throwing a bunch of codes regarding misfires, pressure regulator performance, low pressure fuel rail, etc. Typical sources for these issues include clogged fuel filter, bad fuel pump, bad plugs, bad fuel regulator, and even bad coils. Since I haven't ever changed the plugs or the fuel filter, I started there since I should have changed those as routine maintenance. I changed the coils as well for good measure. $250 later, nothing improved. So I ordered a low pressure fuel pump and a fuel regulator (did I mention I don't have access to proper diagnosis equipment). While waiting for those in the mail, and after a bunch more research, it became pretty clear to me that its my hpfp, not my lpfp. Not wanting to keep semi-blindly throwing expensive parts at the issue, I finally bit the bullet and paid for a proper diagnosis. Another $85, and the verdict came in...high pressure fuel pump. Having already ordered a Hitachi replacement from Rock Auto for $221, you can imagine my chuckle when the shop offered a price for $525 for the pump PLUS labor. I told them I already had a hpfp pump and cam follower coming, which they said they would install for $250.

I've read the Audi service manual, and the replacement seems pretty straightforward except for one thing, and that is the release of pressure on the high pressure side. The manual says I need a diagnostic tester to turn off the fuel delivery while the engine is running to dial down the pressure. I've seen other videos for other Audis where they just remove the pressure sensor and run the engine for 10-15 seconds. I talked to an Audi mechanic who said I can just crack the nut on the high pressure side of the pump and relieve it that way.

Any thoughts on how I can safely relieve the pressure without a diagnostic tester? Any other concerns regarding replacer the pump and follower? Thanks for any productive input!

tcwippy65

Thought I'd follow up on this now that its fixed. Error codes were P0300, P2293, P0301, P0303, P0087, and P2294. Replacing the high pressure fuel pump (hpfp) fixed it. After initially intending on doing the work myself, after about an how spent trying to figure out how to take the thing out, I said screw it. The pump is between the engine and the fire wall and not easy to get to. To lower the high pressure fuel the two options are very gently easing off the nuts on high pressure fuel lines or, more properly, disconnecting the fuel sensor from the hpfp and letting the engine run for 10 -15 seconds. Sense you cant even really see the sensor, much less the tab to pull to release it, I threw in the rag and had be local shop install it. Online I paid about $220 for the pump, $85 for the cam follower, and paid the shop $265 to install the two of them.

HankSun44

Thanks for the follow up post! So many times members fail to take this ever important last step! haha You answered my next question on DIY'ing this thing, "Where is the HPFP!?" haha...will have a shop check and replace this for me.

dreadlocks

On the Gen2 TDI the HPFP is hidden under air intake and behind the EGR and infront of the turbo, its very difficult to see and requires the intake manifold to be removed for access.

Dadster#17

I'm in a similar process. When I turn the key over the engine will crank but won't start. The odd time it will start for a few minutes and will run longer if I give it some acceleration. I disconnected the return fuel line and there was some fuel inside. After connecting it back up and trying to start it again but this time it didn't start, I checked the return line and it was dry. Would this be a sign the HPFP needs to replaced or is there a few other things I should try?

'10Q7TDI_Prestige'

You should do what original poster failed to do; buy a diagnostic scantool so you can properly diagnose the car. Or you can pay a shop to do it once for about the same cost as buying your own device. OBD-Eleven is probably the easiest to use and pretty affordable too, considering what it can do. Until you hook up to this car and see what stored trouble codes are in there, you really have no idea what is going on, and will simply be guessing and flailing about. The computer is tied into everything and can shut down components based on feedback from sensors and/or components, or even a low battery charge status. Read the codes first, then proceed.

frqflyer

Sounds like it may the lift pump. Get a scan tool and manually activate the fuel pump. If you can't hear the fuel flowing or the pump running that is probably the problem.

​​​​​​There is a sensor or some other port, I forget where it is located, but it has a metal screen and if you HPFP grenades you find metal there.

Dadster#17

Ended up getting it to the garage. It was a fuel sensor. They did a bypass on the sensor and it fired right up. I'm told it is hard to get at tho. If I was to go and get my own scan tool what would be recommended if im looking for something to do just the identifying and resetting . Not looking to do any reprogramming. Did some research on the OBD-eleven that was recommended would this be the best way to go?