Bill51sdr

This is on my wife's CLK 350, I seem to recall some mention of a rubber seal or gasket on the fuel tank that can fail and allow fumes to be released. The only time I smell this is after the tank has been filled, it dissipates once the tank empties a bit. Can anyone confirm that this might be the problem? My understanding is that the back seat bottom needs to be removed to access the seal.

gaazmon

mine had a problem like that. the dealer said they found the left fuel level sender unit was seeping through the fuel tank pressure sensor. they replaced the sending unit, fuel filter, and both top seal rings. they stated it took 3.2 hours on my receipt. the cost was covered as i had purchased the car from them and was one of the things i had them cover during the purchase agreement so i have no idea how much they would charge for that. i'd go ahead and change the seals first as that's an inexpensive fix and if that doesn't help move on from there.

blackhouse

Yea I had that same problem a few months back.... All you have to do is lift up ur back bottom seat and the fuel sending unit is on the drivers side.... Unscrew the screws on there and take a look at the top of the unit it may have a small leak/crack on the unit.... The whole replacement part was about 350$ at the dealer.. Its all one big unit so you should be good after that.

Bill51sdr

Thanks guys. This car is well out of warranty so I'll inspect and see what part(s) I need. Hopefully just the seal.

mis3

A few years ago I smelt gas fumes inside the car. The car was still under warranty at the time and they replaced the charcoal canister under the gas cap.

Rudeney

Unless the plastic housing in the sender is broken, it's probably just the seals on the sender and pump access ports. They are very inexpensive:

http://www.parts.com/parts/index.cfm...earch&siteid=2

Bill51sdr

Thank you for the link Rodney. I'll have a look this weekend hoping it is just the seals.

Bill51sdr

Bringing this one up again, the saga continues...

Like others have discovered, the new seal does not necessarily cure this problem! I have a new sending unit I will be installing. Are there any installation guides or diagrams someone can point out for me?

One thing I did find curious about the fuel tank when I had the covers and sending units partially out: The gauge is indicating 1/2 tank, no problem removing the driver's side sending unit as there was little fuel in that side of the tank. On the passenger side I began disassembling the pump unit and found that side of the fuel tank full to the edge of the pump opening in the tank. Needless to say I did not proceed any further as it was clear more fuel needs to be removed from that side of the tank. Is this a normal condition or how this tank is emptied by the fuel system?

Rudeney

Yep, it pulls fuel from from the driver's side, then last from the passenger side. The part that is leaking is the left (USA driver's side), which is the fuel filter. The pump is on the right side. You have open the right side and disconnect the fuel lines from the pump, then remove the filter and fuel lines through the left side.

Bill51sdr

Thanks again Rodney. Yeah the filter ***'y is definitely the leak, my only concern right now is with the passenger side of the tank as full as it was, I could not see where all three fuel lines connected to the pump (one of the clear/opaque ones), which is why I asked about a diagram.

Out of curiosity, how difficult is it to feed the fuel lines and connector from one side of the tank to the other? I will be doing the swap this weekend after more fuel has been used up from the tank.

Rudeney

I haven't done it, but hen I did work on my leak, I had both sides open and it did not seem like it would be too difficult.

Bill51sdr

I will return here after I do the swap and advise in case others find this thread in the future due to similar issues.

Bill51sdr

Today I successfully completed the swap of the fuel level sending unit, it really is not that difficult a task. You definitely need the fuel level to be less than 1/2 tank before beginning or have the ability to siphon off the excess fuel in the passenger-side (right side) tank. The new part has zip-ties around the hoses and wire harness and these should be left in place to aid in feeding the lines and harness to the pump in the right side tank. The entire process took me @ 1 1/2 hours. The only real annoyance was dealing with fuel in the fuel line feeding the sending unit. There was still quite a bit of fuel in the line in spite of the fact that I pulled the fuel pump fuse while the engine was running prior to beginning this task. Once done, off to the gas station... The sending unit functions properly, the tank is full and NO fumes in the garage.

Fatz

Way to go Bill.

I have the same problem and have been putting off the replacement. Will get it done before Fall.

39039

I fixed it.