Jaybird123

My ‘14 E550 coupe now has 105k mi and is running well, however it has developed a persistent gasoline smell outside the car. I do notice it when entering and exiting the driver side, and after being garaged all night the smell is strong. However, no evidence on garage floor and no noticeable drop in mpg (yet). Please share any suggestions asap, as I have multiple 1k+ mi drives coming up in the next month.

I will note that on the last road trip, two unique events occurred, both slightly embarrassing. First, I almost ran out of gas in an apparent gas station desert btwn Baltimore and Cleveland. I’m stunned it didn’t sputter to the pump. Also, I did overfill the tank once due to lack of pump handle overflow function. I could see that causing lingering smell, but not for a week afterwards…? Also, filler on opposite side of car…of course gas maybe ran down some piece of car frame…

I have yet to get underneath it, and perhaps that will shed more light…thoughts??

The_Judge

This is potentially very dangerous, and it needs to be taken care of ASAP. Don't dilly-dally trying to figure it out — take it to a qualified mechanic NOW.

Jaybird123

Thanks Judge, appreciate the response! Have you had similar issue with your E400 coupe?

I’m certainly less inclined to tinker with fuel-related issues in general, just curious if symptoms sound familiar to anyone with similar model (m278, c207, etc). The fuel sender/dual fuel pump design I think these have looks complicated and therefore both expect and wrought with potential causal factors…

our local shops are also quite backed up currently

The_Judge

I haven't had any such problems with my E400, but I'm very familiar with the volatility and indeed explosiveness of gasoline. Not something for the average home mechanic to tackle.

Grant_J

Same here, never had the issue with my 2016 e400. If you can't find the source, don't drive it. If the smell is that strong I wouldn't even keep it in my garage. Very dangerous. On a fuel overflow, you may look to see if there's a puddle of gas slowly evaporating somewhere. Get a loaner or rental for your trips...

Jaybird123

Evidence of leak after removing panel in front of driver side rear wheel

Gas on tank, clearly coming from top of tank

Bingo. Almost a pint surrounding fuel sender unit under backseat on driver side

Jaybird123

Obtained replacement rubber o-ring from local dealer, off to pick up sender pump in the morning. Removing those lock rings is not much fun, agree with another post here that proper removal tool is essential