N51 fuel tank,fuel pressure loss

image Today this car kicked my ass,,,,finally figured out the problem,,,,2011 E90 N51 engine,,,,,check engine light on,,,the fault was lean mixture bank 2,,,, so I checked adaption values,,,,found bank 1 at 8% and bank 2 at 9%,,,,so I smoke tested the intake system no leaks,,,smoke tested the exhaust system no leaks,,,,I smoke tested the valve cover no leaks,,,,I then checked the oil cap and found to much vacuum inside the engine,,,,so I replaced the valve cover,,,I reset the adaption values and test drove the vehicle,,,,the fault came back with the same problem,,,,,so the next day I started all over,,,,but I noticed when I started the car up the next morning,,,,the idle surged slightly,,,,almost like it was a misfire,,,,so I tossed in some ignition coils,,,,that did not fix the problem,,,,so I re smoked the intake and valve cover again to make sure I didn’t miss anything,,,,so I went back to basic,,,,air,fuel,and spark,,,,I never checked fuel,,,,I checked the fuel pressure,,,,ok I have a problem 3.5 bar pressure,,,,it should be 5.0 bar,,,,,I remove the fuel tank cover to expose the fuel pump.image So I looked inside the fuel tank,,,,,look what I found,,,,my problem that kicked my ass,,,,look at the short rubber hose inside the tank,,,,notice a small cut in the hose,,,,that’s my fuel pressure loss,,,,the only fix is to replace the fuel tank,,,,the hose is built in to the fuel tank.image Here the new fuel tank,,,,it looks like they changed the hose to a differs type of rubber hose so it won’t crack again.

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18 Responses to N51 fuel tank,fuel pressure loss

  1. a.a. says:

    Looking back, is there anything you could have done differently to lead you in the direction of the problem sooner?


    • Hahaha good question,,,,,I wish I would have checked fuel pressure sooner,,,,but as a BMW tech,,,,we have seen the valve cover go bad more often then the gas tanks,,,,,I guess I just went for what is the most common problem ,,,,,instead of checking all 3 things first,,,,fuel,spark and air.




  3. Christopher says:

    I have the same problem now.How hard do you think it will be to replace that hose?I want to try that instead of replacing the whole tank.


    • I don’t know if you can just replace that hose,,,,the hose camps will have to cut off carefully and you don’t want to break the plastic fittings,,,,and while cutting no sparks please because of the gasoline,,,,this doesn’t sound like a good idea.


      • James says:

        Is the standard N52 (not SULEV) immune from this problem? I have avoided CARB compliant models as a rule due to the extra complexity and cost down the road. I know the M56 can be much more costly to repair for even minor problems such as a fuel pump when compared to the M54 due to California’s emissions requirements.


      • Yes I believe it is immune


  4. amanda says:

    My 2009 328 ixdrive sulev didn’t start the other day, was told it was fuel pump,after guy banged under my car while I started it and went on,but didn’t turn on again the next day. what is the process for replacing fuel pump.


    • To gain access to the fuel pump,,,you have to remove the rear seat bottom and there is a panel that has to be removed on the right side,,,,,you will need a special tool to remove the fuel pump cover.


      • Amanda says:

        This is the repair that was done can you give me your advice :
        Install repair kit in tank right side to delivery hose
        delivery unit right
        repair kit-16-11-7-301-984–qc retainer-16999911
        replaced fuel pump-1614610
        repair kit-1699000

        Since I got the car back I get horrible gas mileage -before I would get 400 miles to a full take,now 350 miles.

        I have a 2009 328i xdrive coupe sulev n51-


      • The repair looks to be correct,,,why you are getting bad gas mileage I don’t know,,,,,it could be something else with the engine causing bad gas mileage


  5. AMANDA says:

    Question stated in SI-B-12-21-10 if you don’t get pressure from fuel hose ,it states to replace the fuel tank. So why didn’t they do that with my car. Also what is the difference in fuel tank repair and delivery unit-right. Also can a leaking valve cover gasket drip oil onto the oil pan. What are some reasons OIL PAN GASKET LEAKS.


    • Each vehicle is different on repairs,,,not all the cars are the same,,,,yes the valve cover gasket could leak down the backside of the cylinder head down to the oil pan,,,,the only way to check and see if from look up from under the engine and look at the back of the cylinder head and follow the oil leak,,,,the oil pan also leaks the reason is age,miles and heat,,,,,because the gasket get hard and brittle and starts to leak oil


  6. AMANDA says:

    I have a 2009 328i xdrive,low emission car with .


  7. Bamabimmer says:

    I am capable of doing the work myself as far as to change the tank. Have had no luck in finding n51 tank though. Would using an n52 tank work or are the pumps different as well in general? Or could I use n52 tank and pump? Do you have the part number for an n51 tank and could I use my existing n51 pump in a new tank? Have heard they are made in such a way it is not possible.


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