The flex fuel 2014 E350 (3.5L engine 212.059 non PZEV) has a saddle fuel tank (higher is middle to allow for driveshaft), The are two fuel pumps, the passenger side pump is a transfer pump from passenger side to drivers side, the passenger pump (part 218-470-03-94 ) is completely inside the tank except for the sealing cover. The drivers side pump delivers the fuel to the high pressure fuel pump in the engine bay (part 218-470-06-94 about $220 online genuine Mercedes) and has a nipple on top connected to the fuel supply hose. Both pumps have a large o-ring that seals the covers to the tank (part 025-997-1845 about $25ea if you can find them) and a locking ring to compress the lids.

In my case, the nipple on the drivers side pump cracked and fuel was leaking onto the top of the tank. The garage smelled strongly of gasoline although inside the car was not too bad.

You must have a special tool to release and install the locking ring. I got mine on Amazon 6599 Locking Ring Tool for about $20. You will not be able to do this job without this tool, it takes about 200 ft lbs to release and reseat the locking ring.

You have to remove both pumps because they are interconnected in the tank with hoses. I did not replace the transfer pump but I did replace the o-ring. Make sure the fuel tanks are ¼ full or less.

Here are the steps and check list:

1. Roll down all the windows (because you are disconnecting battery)

2. Disconnect battery

3. Fuel tank must be ¼ or less

4. Remove back seat by pulling up on the front on each side and then remove.

5. Remove the two covers under the back seats to expose the tops of the pumps

6. Disconnect the electrical connectors and move them to side

7. Disconnect the fuel line by pressing the small release button on the side near the base of the fitting

8. Although you can’t install the pump orientation wrong. I marked everything to ensure I knew the orientation of the pumps

9. Break loose the locking ring using tool 6599 on passenger side first. This will take a breaker bar and you’ll have to jerk it hard to get past the indents on the locking ring. The cap on the transfer pump slides in/out of the main pump so don’t be surprised or worried if it comes apart when lifting out, the spring legs just hold the pump down in tank. There are two electrical connectors but you can leave them connected and move lid out of the way. Unclip one hose on the basket and push button to release the hose connected to nipple. Attach a 4’ pull wire to the two hoses you just disconnected.

10. Release the locking ring on drivers side. Pull the pump assembly out with the pull wire.

11. Put the new o-rings in place on both sides.

12. Attach pull wire to hoses on new pump. Gently pull the hoses to passenger side while working the pump into the tank opening. If you forget pull wire you can reach your hand inside and guide the hoses.

13. Reattach the quick connect to nipple on passenger pump, clip the other hose to side of the basket. Slide the cap legs back into their holes.

14. Reinstall both locking rings, make sure they are fully seated, Expect to have to apply a jerking force.

15. Attach quick connect fuel line to drivers supply nipple.

16. Attach electrical connectors both sides

17. Reattach battery and start engine, check for leaks

18. Reinstall covers and back seat.

I kinda knew what to expect and encountered no surprises and it took about an hour. But this design is different than most of the videos I’ve seen out there. Senior Leigh has a good video but his 350 is a diesel and the pumps and replacement is completely different I think most gas powered cars in the US have this design maybe up until 2016 since the design was basically the same. Hope this info helps someone.

 

Thank you for the writeup. I was wondering, do you need to disconnect both the positive and negative battery cables or just the negative. Any codes or issues upon reconnection? Also what about Aux battery and why do the windows need to be down? Thank you.

 

Strong smell of fuel in garage but not in car 2014 e350 W212, This write up is fantastic and very helpful, all great information.
I believe after inspection of my 2014 e350 that it possibly falls under the:
NHTSA Recall Campaign 15V792000.
Recall Summery 15V-792/2015110006 12/28/2015
Recall Solution 15C-/2015110006 04/07/2026
This is predicated on the Birthdate of the 2014 Model 06/04/2014 to 07/09/2014 Requires dealer to confirm birthdate of the Car in question.
I removed the rear seat and began to smell fuel but only after removing the outer covers from drivers and passengers sides did the smell increase.
both sides has residue from a fuel leak leaving the surface filthy. but obviously not clean and dry as it should be.
I attempted to clean both sides just to see and changes moving forward, sort of a bench mark. plan is to visit the dealership after the internet research and start gathering factory OEM part# so I can make the decision if I want to do the work if the dealership declines to make the repairs under this factory recall, again as previously satiated the repairs are supposedly predicated on the build birth day of the car.
That all said, I had the same problem with my 2009 e350 sedan and after dropping it off at the dealer for them to look and decide what to do or how to handle this problem, It was all warranty recall repaired. No Charge.






I will attach the NHTSA documents, I home this helps