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Thread: external/transfer fuel pump on my RS6 died after 68k miles-any suggestions?

  1. #1
    Registered User ramin's Avatar
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    external/transfer fuel pump on my RS6 died after 68k miles-any suggestions?

    Hello All,

    This is only the second (non tune) problem after a battery change for me. Otherwise the beast has been running great!

    It went from running fine to hesitation when pressing the accelerator. If you press the pedal, it will act like it's dying, but if you ramp up the speed slowly, it will keep going faster and faster. Interesting, the car runs even with a dead fuel pump. To be specific this is the transfer/external fuel pump. The pump in the tank runs fine and vibrates the gas tank.

    The culprit seems to be the electric connector. It is a pretty weak design. I will post pictures once I get all the parts off and exchanged. Basically, the connector wires attached to the pump body are encased in a relatively thin plastic casing. The wire is very short too, so if there is any play in the pump, it could cause the connecter body to snap off. In any case, the pump doesn't even run with direct power to it (with the connector totally snapped off), so I am not 100% sure which happened first. I guess a bad/loose connection could eventually kill the pump.

    What are your suggestions for changing the transfer fuel pump? I would like to stay OE and away from modifying too much as the pump has worked fine for 68k.

    The local dealer wants $840 for a new one. I found ECT Tuning has an after market part for $140 http://www.ecstuning.com/Audi-RS6--4...nce/ES2189784/

    It looks like the ECT part needs some minor wiring modification, stripping, new connector and mounting.

    Also worth mentioning, the screw and nut that held the fuel pump strap in place were fused together and I had to cut off the screw. Pretty weak design there too. The ECT pump comes with two new straps. And, I plan to add a couple of zip ties as backup.

    Please let me know if you have any suggestions for getting the OE pump (haven't totally disconnected the pump yet so if you have the part number handy I would appreciate it!) at a more reasonable price, any aftermarket pumps, or experience with the ECT pump.

    For the sake of documenting the problem, I got the following 8 fault codes:
    8 Faults Found:
    17473 - Fuel Pressure Regulation
    P1065 - 008 - Regulation Discrepancy
    16684 - Random/Multiple Cylinder Misfire Detected
    P0300 - 001 - - MIL ON
    16685 - Cylinder 1
    P0301 - 001 - Misfire Detected - MIL ON
    16687 - Cylinder 3
    P0303 - 001 - Misfire Detected - MIL ON
    16686 - Cylinder 2
    P0302 - 001 - Misfire Detected - MIL ON
    16688 - Cylinder 4
    P0304 - 001 - Misfire Detected - MIL ON
    17536 - Fuel Trim; Bank 1 (Mult)
    P1128 - 001 - System too Lean
    17538 - Fuel Trim; Bank 2 (Mult)
    P1130 - 001 - System too Lean
    Readiness: 0010 1101
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  2. #2
    Registered User ben916's Avatar
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    uh well, you could upgrade the external fuel pump with the Bosch 044 one, it does require some modification to the wiring harness - but you are looking that way anyway.
    If you search on here for threads that do have the 044 Bosch fuel pump (5 bar), you should find it.

    or -> http://www.034motorsport.com/fuel-in...s-p-19543.html not 100% sure this is the one but it gives you an idea.
    SOLD - 03 RS6 Avus (905355)
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  3. #3
    Registered User ramin's Avatar
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    Thanks I read about that but don't really want to change the piping. By the way, ECT lists the 044 Bosch pump at 3 bars only. Not sure if 044 refers to multiple pumps.

    http://www.ecstuning.com/Audi-RS6--4...ance/ES514125/
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  4. #4
    Registered User kday's Avatar
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    The 044 is a beast of a pump. It's also really loud. As I recall, the RS6 fuel pump(s) are modulated so that when not under load they aren't run at full voltage, which mitigates this somewhat. Not sure how that would work with an aftermarket pump though.

    Did you check the genuineaudiparts.com for the OEM pump? Probably still expensive, but might be less than your dealer.

    Regarding the pump pressure, the pressure varies with flow. I have data showing the 044 pump delivering well over 500 kPa, but that was into a 5 cylinder with smallish injectors.

  5. #5
    Registered User ramin's Avatar
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    Quote Originally Posted by kday View Post
    The 044 is a beast of a pump. It's also really loud. As I recall, the RS6 fuel pump(s) are modulated so that when not under load they aren't run at full voltage, which mitigates this somewhat. Not sure how that would work with an aftermarket pump though.

    Did you check the genuineaudiparts.com for the OEM pump? Probably still expensive, but might be less than your dealer.

    Regarding the pump pressure, the pressure varies with flow. I have data showing the 044 pump delivering well over 500 kPa, but that was into a 5 cylinder with smallish injectors.
    Thanks Kday, I checked genuineaudiparts.com for the OEM pump but they don't have the RS6 in their catalog. I need to pull the pump and remove the protective sleeve to get the part number first. Of course, if you know of an easy way to figure out the part number, I would appreciate knowing how. I just didn't want to deal with the gasoline leak until I have the replacement part, so I left it hooked up to the pipes for now.

    Also, does anybody know what pressure the OEM pump puts out? I kind of like the smaller pump from ECS tuning (both price and mounting configuration) but I am not sure if 3 bars would be too much with the original pipes. I called ECS but the guy on the phone was kind of clueless as to how well of a fit this one is for RS6. http://www.ecstuning.com/Audi-RS6--4...nce/ES2189784/
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  6. #6
    Registered User ramin's Avatar
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    By the way, Kday's point about the variable voltage and resulting pressure is correct. So, the 044 pump would act differently depending on the voltage supply. In the RS6, the harness only feeds the transfer pump about 10V at normal speeds and increases the supply to 12V at start-up (for 1 second) and if the car is under acceleration. So, the Voltage feed to the transfer pump is definitely variable by 2-3 V (it's in the VAG manual and I verified it with a voltmeter to make sure there was no problem with the controller logic feeding the pump).

    I did some more searching and JCWhitney has a few inline fuel pumps too that they claim match RS6. But, not knowing the exact OEM part specs/pressure, I am hesitant in trial and error with the fuel supply
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  7. #7
    Registered User lswing's Avatar
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    Here's the ETKA, think this is the external pump you want. Looked up the price, yikes! Cool how it has a sound absorber shroud.

    As a side note, I've been logging my injectors recently, and stock fueling seems to have them at 70% under full load. I upped my fuel under load to 110% and the injectors logged 76%. I have been wondering how much fuel the stock pump can push. Enough to have the injectors 85%?

    http://genuineaudiparts.com/parts/in...&siteid=214407

    Click image for larger version. 

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    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

  8. #8
    Registered User ramin's Avatar
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    Some more info on the fuel pump, the part number is 4B0906089A (sold by http://www.genuineaudiparts.com for $627, a lot cheaper than the dealer) and VAG manual says minimum of 500 cm3/15s flow which translates into 120 liters/hr.

    The lower end billet pump (for up to 500 hp) that ben916 mentioned has the following specs (the 044 is obviously a lot more potent):

    Bosch 040 "High-Output" 500 Horsepower-Capable
    Flow at 55 PSI: 175 LPH
    Flow at 75 PSI: 155 LPH

    So, I am not sure if this would be too much pressure for the existing OE piping. Any idea on the upper limit for OE piping? 155 LPH is very close to the minimum of 120 LPH mentioned in the manual.

  9. #9
    Registered User ramin's Avatar
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    Thanks Lswing, your link has the same part number as the one I posted a minute after yours

    The Bosch 040 (not 044) seems like a decent upgrade because it doesn't suggest any other mods other than the terminals, but I still need some info on whether it will burst the existing pipes at that rate. I am going to look at the pipes again, I think they have a PSI rating on them.
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  10. #10
    Registered User lswing's Avatar
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    Glad to help Keep us posted on the details, good info! Any idea if the injectors can outpace the stock pump? There is some math that I need to work on....
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

  11. #11
    Registered User Ms_RS6's Avatar
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    Quote Originally Posted by kday View Post
    The 044 is a beast of a pump. It's also really loud. As I recall, the RS6 fuel pump(s) are modulated so that when not under load they aren't run at full voltage, which mitigates this somewhat. Not sure how that would work with an aftermarket pump though.

    Did you check the genuineaudiparts.com for the OEM pump? Probably still expensive, but might be less than your dealer.

    Regarding the pump pressure, the pressure varies with flow. I have data showing the 044 pump delivering well over 500 kPa, but that was into a 5 cylinder with smallish injectors.
    I do have the 044 Bosch Fuel Pump installed. It is a little loud, specially when you are running low on gas. I haven't had any issues with it. I decided to upgrade it since I was thinking of going with a full stage 4 MTM but was afraid of upgrading turbos since it is really expensive and labor intensive (and I didn't want to mess with anything major unless it was broken . I have Wagners, colder plugs, MTM Exhaust and recently gutted the downpipes. Anyway, I'm not too car technical and wish I could answer more questions about the pump but again, it hasn't given me problems and I have had it installed for more than 20k miles.

  12. #12
    Registered User ramin's Avatar
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    Quote Originally Posted by Ms_RS6 View Post
    I do have the 044 Bosch Fuel Pump installed. It is a little loud, specially when you are running low on gas. I haven't had any issues with it. I decided to upgrade it since I was thinking of going with a full stage 4 MTM but was afraid of upgrading turbos since it is really expensive and labor intensive (and I didn't want to mess with anything major unless it was broken . I have Wagners, colder plugs, MTM Exhaust and recently gutted the downpipes. Anyway, I'm not too car technical and wish I could answer more questions about the pump but again, it hasn't given me problems and I have had it installed for more than 20k miles.
    Hi Ms_RS6, thanks for the info. Did you install the 044 in-line outside the tank (there seems to be another similar looking pump that goes on the inside of the tank - the direction from 034motorsport sent by Ben 916 shows the pump installation inside a fuel tank)? If we are talking about the fuel pump that is installed outside the fuel tank, two more questions: (1) does the 044 fit in the old slot for the OE pump? (2) did you end up changing the OE piping?

    Incidentally, I found the pressure requirements in the VAG Manual. The pump needs to deliver 0.8 to 1.3 bar to the fuel rail for OE set up.
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  13. #13
    Registered User Ms_RS6's Avatar
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    Quote Originally Posted by ramin View Post
    Hi Ms_RS6, thanks for the info. Did you install the 044 in-line outside the tank (there seems to be another similar looking pump that goes on the inside of the tank - the direction from 034motorsport sent by Ben 916 shows the pump installation inside a fuel tank)? If we are talking about the fuel pump that is installed outside the fuel tank, two more questions: (1) does the 044 fit in the old slot for the OE pump? (2) did you end up changing the OE piping?

    Incidentally, I found the pressure requirements in the VAG Manual. The pump needs to deliver 0.8 to 1.3 bar to the fuel rail for OE set up.
    Here's the install and DIY link of when it was done to my car.
    http://www.rs6.com/showthread.php/21...sure-regulator

  14. #14
    Registered User ramin's Avatar
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    Great, thanks Ms-RS6!

    Did you also change the regulator (to a 5 bar one) and flash your ECU? The last comment on the thread you sent V8weight says " It may be kind of hard on the pump however, trying to push all that extra volume through a 4bar regulator."

    By the way, found the answer to whether the Bosch 044 pump fits inside the tank. Apparently it does with some modification (not sure what kind/how much modifications though).
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  15. #15
    Registered User Ms_RS6's Avatar
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    Quote Originally Posted by ramin View Post
    Great, thanks Ms-RS6!

    Did you also change the regulator (to a 5 bar one) and flash your ECU? The last comment on the thread you sent V8weight says " It may be kind of hard on the pump however, trying to push all that extra volume through a 4bar regulator."

    By the way, found the answer to whether the Bosch 044 pump fits inside the tank. Apparently it does with some modification (not sure what kind/how much modifications though).
    I did change the regulator as well to a 5 bar. I also flashed the ECU.


    -Maria

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    Registered User kday's Avatar
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    No need to worry about bursting the lines. Even if it was possible for the pump to develop that much pressure (it's not), the job of the fuel pressure regulator is to keep that from happening.

    I guess if you put an 044 in the tank you could just bypass the external pump entirely.

  17. #17
    Registered User ramin's Avatar
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    Quote Originally Posted by kday View Post
    No need to worry about bursting the lines. Even if it was possible for the pump to develop that much pressure (it's not), the job of the fuel pressure regulator is to keep that from happening.

    I guess if you put an 044 in the tank you could just bypass the external pump entirely.

    Yep, kday, you are correct. I think I was misreading the original thread about installing the 044. The issue was raised that if you don't use a "high pressure" hose (i.e., one rated for fuel injection) it may burst. I wasn't thinking at all and that what's there already is fuel injector hose rated at 180 PSI plus.

    I found the top flow number in the manual too. It is 600 cm3/15s at 13V (ramping up from the minimum of ~320 cm3/15s at 9V). So the flow range between 9V and 13V (which is controlled by the fuel control module J538) goes from 78 liters/hour (20.6 gal/hr) to 144 liters/hour (38 gal/hr) for the stock set up.

    Since 044 Bosch pump requires reflashing the ECU with the 5 bar regulator, I need to first call APR because I have their ECU.

    So, I will spend the weekend trying to figure out if I can find a pump that matches the flow of the stock set up to avoid dealing with a reflash.
    ----------------------------------------------------------------------
    2003 Audi RS6 with APR exhaust and APR ECU stage 1; Mugello Blue

  18. #18
    Registered User ramin's Avatar
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    Thanks Maria, I am going to some research to see if I can avoid a reflash of the ECU

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