After filling up my wife's CLK 500 it emits a fuel odor. What should I be looking for? There is no gasoline leakage that is easily visible. She has told me several times that her garage smells like gasoline after she fills up.

 

When I had the same symptoms, it was the fuel tank pump seal. I just stopped filling it by a gallon or 2 until I had the seals replaced when I had the car being serviced for another issue.

I think it is a not difficult diy. On the 550 you just have to remove the rear seat to access the top of the fuel tank. You can then access the pump and replace the seal between it and the tank.

 

It's one (or both) of two possible problems. First, as Fatz posed, the seals on the fuel sender and pump can leak. They have been redesigned to be thicker. The other is that the sender itself is leaking. Pull the rear seats out and then remove the access covers. The sender is on the left side, pump on the right. If you see fuel or stains from fuel, on the top recess of the sender housing, then it is leaking. The proper solution is to replace it, but honestly, that's a major pain. Instead, you might try just coating the top of it where it leaks with a proper fuel tank epoxy.

 

If it is the sending unit leaking on top like my 2009 CLK550 the epoxy worked great . I cleaned and dried it well and applied some epoxy I had in my tool box and the smell was gone. It has been 3 months and many fill ups.

 

That part is available separate.

 

Yes, you can buy just the sending unit. However, it has wiring and hoses that run through the tank to connect to the fuel pump. There is a connector for one the fuel line that attaches to the pump and over time, it becomes very brittle. When trying to remove it, it is often stuck and you end up breaking the plastic nipple on the pump, and then you need to replace the pump. So, with discounted parts, you're looking at $500 for a pump and sender unit, plus having to deal with the risks of working with the open fuel tank. Or, you can by a $5 tube of epoxy...

 

So sketchy

 

yea, there are a few posts about it...

here is one where there are some pics.

https://mbworld.org/forums/clk-class...tructions.html