C280 Sport

So about a week about I filled up my CLK 350. Topped it off drove it home. Parked it. Decided to drive it to work today but I noticed a little bit of a fuel smell on my way to work. It is very cold -5' here. No smell really inside the car but on the outside I smelled a little bit. No leaks at all under the car. No gas gauge dropping. Is it just me or was I stupid enough to on accident overfill it and now it will smell under the fuel is used up?

2009 CLK350 Coupe.

faded1004

pop open the bottom of the rear seats. the seals on the top of the gas tanks go bad often i think. i changed mine because of this.

if you smell that area, like pop forward the butt cushion... and i smelled it there. i would start there...

Rudeney

There are two possible problems. One is that the seals on the sender and fuel pump units can fail and leak. They should be replaced as the revised seals are thicker. The other issue is a leak where the pressure sensor attaches to the top of the sender (see image below - it's the black connector at 11 o'clock). Unfortunately, that is not a separate part, so the entire sender unit must be replaced. And when you replace it, you have a good chance of breaking the nipples on the fuel pump where the hoses connect as they will be brittle. I did this job on my CLK550 and ended up replacing both the sender and pump, and both seals. My advice, if it is the pressure sensor, clean it thoroughly and coat the area with gasoline-proof epoxy or similar sealant.

C280 Sport

Issue solved. I overfilled the tank like a jerk. Filled up today and no smell at all

Rudeney

The saddle-style tank is designed so that you fill it on the right (pump) side. Once that half is full, it then "spills over" to the left (sender) side. Fuel is first pulled from the sender side of the tank, and last from the pump side. Since it's the sender that leaks, you may only smell gasoline when the tank is filled, and then it goes away after the first gallon is used. This can lead you to believe the smell is because you overfilled it. Maybe you did, but this leak is VERY common, so keep an eye (well, nose actually) on it.

Also, it won't take but a few minutes to check this. Remove the two bolts holding the front of rear seat cushion in place, then remove the screws for access plate underneath and you can see the top of the sender as in the picture I posted above.

mbw10dah

On the top of my sender, it appears fuel is leaking somewhere beneath that black connector at 11 o'clock, the pressure sensor. I don't see any cracks, so maybe it's leaking from somewhere underneath the sensor. Does that sensor pull off, so that I can inspect underneath it? Otherwise, how do I go about patching it up with the gasoline-proof epoxy?

gaby

Thnaks for your post . I have the exact same problem on my 2007 Mercedes CLK 350 . where did you buy your parts and how much cost you . Thanks .

C280 Sport

I did not actually have the issue. I just overfilled it. Check pelican parts.com or even autohus.az

Merc Mania

Forgive this minor digression from the usual programming today. To us CLK owners, Rudeney is the Oracle whose learned auto repair insights have over the years saved many CLK owners more repair money than can ever be quantified. Greetings and hallucinations from an unrepentant CLK jockey living well off the beaten path, way out in the sticks that lie deep in the boonies, and far beyond the pale.

This test of the emergency broadcast system is now complete, and normal transmissions can resume without further ado.

Scotslad2k

I just fixed this issue with my CLK 550 you will want to pull the back seat and remove the 3 access covers and see if any fuel is pooling around the transfer pump or fuel pump, sometimes it is just the seals but in my case transfer pump was leaking regardless of fuel tank level

Scotslad2k

Scotslad2k

TRQ sender unit part from partsgeek$120 and seals $20