Results 1 to 10 of 10

Thread: Low pressure fuel pump?

  1. #1
    Santana 3000 FTW! FlyBoy's Avatar
    Join Date
    Jul 2005
    Location
    Calgary, AB
    Posts
    598

    Default Low pressure fuel pump?

    I have been having misfire/stuttering issues for some time now that were very intermittent but seem to be getting worse. I went on a road trip a few weeks ago and a few times had what felt like a fuel cut while doing 120 on the highway: driving along at constant speed, give it some gas to go up a hill, speed up a little and then nothing, down shift and still nothing, lose some speed, and then it recovered and accelerated fine.

    It has thrown random/multiple cylinder misfire codes and each cylinder misfire codes, and a couple of times:
    Fuel Rail/System Pressure P0087 - 002 - Too Low - Intermittent

    I have replaced all of the ignition coils, spark plugs, cam follower, checked electrical grounds, diverter valve, cam follower and high pressure fuel pump shaft, etc. The fuel filter was replaced a couple of years ago so it shouldn't be that.

    Today I ran vag-com logs over two 1/2 hour trips and found the low pressure fuel pump sits at 4.5 bar and 50% electrical load all the time regardless of engine load. Pressure dipped to 4.2 bar once and hit 5 a couple of times, but other than that hovered right around 4.5 regardless of pressure in the high pressure rail (ranged from 70 - 110 bar). The service manual says output from the low pressure pump should be 3-7 bar, but I would expect some movement in that range right?

    So I'm thinking the low pressure pump isn't putting out enough for the high pressure pump to keep up with but want to confirm that this behaviour is in fact weird. Thoughts?
    Jeff
    Current: 2017 Audi A4 2.0T Quattro S-Line
    Previous: 2007 Audi A4 2.0T Quattro S-Line, 2001 VW Jetta

  2. #2
    Registered User Natty54's Avatar
    Join Date
    Oct 2009
    Location
    Calgary
    Posts
    2,197

    Default Re: Low pressure fuel pump?

    Usually with that code my first step is the cam lobe. Which you already changed. Unless the actual cam was worn?

    Other things to check:

    - Check actual fuel pressure at rail with tool and compare to sensor if it is lower / same change fuel pump. If its higher change sensor.
    - Also fuel filter - when was it last changed?
    Now offering detailing services!! http://www.gtrauto.ca/detailing-services.html

    United Motorsport, Kerma TDI, KW, APR, COBB, Magnaflow, K&N, AFE, Motul, Lubromoly, Sonax, Air Lift, HPA, Ohlins, Klutch Wheels, Remus Exhaust

    info@gtrauto.ca / www.gtrauto.ca / GTR Auto Facebook

  3. #3
    Santana 3000 FTW! FlyBoy's Avatar
    Join Date
    Jul 2005
    Location
    Calgary, AB
    Posts
    598

    Default Re: Low pressure fuel pump?

    Cam didn't look/feel worn, but its a pretty small hole to look in. The new follower didn't have any noticeable wear on it.

    Fuel filter was last done 3 years / 50k km ago. Thought it was on the regular maintenance schedule but don't see it now. I suppose it could be that, but I would have thought the pump would work harder if it was clogged but the electrical load seems to jive with the output.

    Why don't you PM me a quote for a pump and filter Natty.

    Thanks.
    Jeff
    Current: 2017 Audi A4 2.0T Quattro S-Line
    Previous: 2007 Audi A4 2.0T Quattro S-Line, 2001 VW Jetta

  4. #4
    Registered User Natty54's Avatar
    Join Date
    Oct 2009
    Location
    Calgary
    Posts
    2,197

    Default Re: Low pressure fuel pump?

    Done!
    Now offering detailing services!! http://www.gtrauto.ca/detailing-services.html

    United Motorsport, Kerma TDI, KW, APR, COBB, Magnaflow, K&N, AFE, Motul, Lubromoly, Sonax, Air Lift, HPA, Ohlins, Klutch Wheels, Remus Exhaust

    info@gtrauto.ca / www.gtrauto.ca / GTR Auto Facebook

  5. #5
    Registered User clover168's Avatar
    Join Date
    Jan 2010
    Location
    Calgary
    Posts
    38

    Default Re: Low pressure fuel pump?

    It might be carbon build up too. I had the same problem with my Q7, changed every you have mention and still the same and they couldn't figured out why. At the end they clean the ports and problem solved.

  6. #6
    Santana 3000 FTW! FlyBoy's Avatar
    Join Date
    Jul 2005
    Location
    Calgary, AB
    Posts
    598

    Default Re: Low pressure fuel pump?

    I did consider carbon build up, and will have the intake off soon to clean it out as well. I put a boroscope in the intake but couldn't get past the divider plates to actually see the valves. I ran a can of SeaFoam through but it didn't seem to do anything, didn't have high hopes for it in the first place. It was the fuel system codes that lead me to think it's the pump. I pulled the seat out and checked the supply voltage to the pump yesterday, it's good.
    Jeff
    Current: 2017 Audi A4 2.0T Quattro S-Line
    Previous: 2007 Audi A4 2.0T Quattro S-Line, 2001 VW Jetta

  7. #7
    Santana 3000 FTW! FlyBoy's Avatar
    Join Date
    Jul 2005
    Location
    Calgary, AB
    Posts
    598

    Default Re: Low pressure fuel pump?

    Cleaned the carbon last week, no change. Changed the low pressure pump and filter today, no change. I wonder if my car is covered by the extended warranty on the cams.
    Jeff
    Current: 2017 Audi A4 2.0T Quattro S-Line
    Previous: 2007 Audi A4 2.0T Quattro S-Line, 2001 VW Jetta

  8. #8
    Registered User clover168's Avatar
    Join Date
    Jan 2010
    Location
    Calgary
    Posts
    38

    Default Re: Low pressure fuel pump?

    Name:  uploadfromtaptalk1443419123792.gif
Views: 102
Size:  84.9 KB

    Have to try all those thing yet?

  9. #9
    Santana 3000 FTW! FlyBoy's Avatar
    Join Date
    Jul 2005
    Location
    Calgary, AB
    Posts
    598

    Default Re: Low pressure fuel pump?

    Update: Took my car into the dealer in Vancouver last month. They replaced the intake cam, HPFP and cam follower under warranty. STILL MISFIRED!! Only at idle now though. They worked on it for 2 more days and could not find the solution. I got it home, and the misfires were all being logged on one cylinder. Swapped coils, no change. Swapped plugs, misfire followed. Was a bad plug, the dealer didn't suspect it could be the problem because it was a new plug. So the major problem is all fixed, but now I get intermittent slow response codes on the cam adjuster valve (N205). Hooray.
    Jeff
    Current: 2017 Audi A4 2.0T Quattro S-Line
    Previous: 2007 Audi A4 2.0T Quattro S-Line, 2001 VW Jetta

  10. #10
    eat-quattro-sleep PRY4SNO's Avatar
    Join Date
    Jul 2007
    Location
    Edmonton
    Posts
    1,883

    Default Re: Low pressure fuel pump?

    Find one problem, fix another. That's a game I know well.

    Still though. Good work being persistent and finding the cause.
    Find me on Instagram @pry4sno

    Candy White 2010 VW Golf Sportwagen TDI 6 speed /// #farmenwagen
    Indigo Pearl Effect 1992 80q 20v /// Eventual AAN'd Winter Sled
    Brilliant Black 1990 Coupe quattro /// Because Racecar

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •