Fuel smell from rear of 500SL

[G-Benz]

My wife complains of strong gasoline fumes, and it seems to come from somewhere in the rear of the car. It is strongest in the passenger side, but only if the fuel tank is not completely full.

Is there a venting system that I sould be aware of, and if so, any cracked lines, location of them, etc. to look for?

[STEANSON]

You should get this checked....I lived with the smell until I saw a puddle...I believe the 129's (not sure if different with the 300's and 500's) have 2 fuel pumps...and my external pump was broken and leaking gasoline. It was not enough to impair performance, but my milage obviously suffered eventually, and the sight of the puddle was very scary. Apparantly the fuel stayed "on the car" on a pan or something until it just began pouring out. Good luck.

[Gilly]

Seems to me I had a 129 doing just as Steanson is saying. It came in for the same complaint, but I saw nothing dripping on the ground. I raised the car up on the hoist while running and removed the small panel under the fuel pump assembly. I could see a fuel stain on the "top" of the panel (the side facing the pump assembly). I tweeked around with the hoses and was rewarded with a pretty healthy "squirt" from one of them. At times I'm sure it was spraying out all by itself. The fuel pump assembly is located in front of the rear axle on the passengers side of the car, so it sounds like the evidence is pointing towards a leaky hose near the fuel pump someplace.
Gilly

[G-Benz]

Last night I backed the car out of the garage, and I crawled underneath while it was running to see if I could find anything. Sure enough, at the location you all have described was a steady trickle of gasoline dripping off of the seam of the fuel pump pan.

I plan to put the car on jackstands tonight and investigate further.

Any surprises? Like the pan being held in place with Torx bolts. Are the fuel hoses rubber metal or braided? And why the hell isn't there a manual for working on these cars?

[STEANSON]

When mine blew I took it to a shop....they replaced it and gave me the smelly broken fuel-pump. I could not tell where it leaked from, however, they told me that the bearings give out and it leaks from the pump itself. The thing looked like any pump off my mustang (I guess being a Benz I wanted to see something with "geegaws" and "hoodi-hoos"). I believe the lines on mine are just rubber...but mine is just a little '90 300...Next time it WILL be DIY project, but I share your amaze and disgust in the lack of a manual...or maybe just frustration...I think once you get under it it should be a relatively simple task...good luck.

[Gilly]

G-Benz:
The panel under the fuel pump is held on by about 4 10mm plastic nuts. The hoses are rubber, It could be that a simple tightening of hose clamps will fix it. I can't remember if that's all I did on the problem I had on a 129 or not. Almost seems to me the hose may have been rubbing somewhere and sprung a leak in the rubbed area.
Steanson, I think you were given some sort of story about your fuel pump/pumps. Bearings can eventually go out and the pump will get noisy then stop working, especially if the car is regularly run out of fuel. But never a leaking pump. Never say never, but this seems highly unlikely. Someone wanted to sell you a pump rather dearly.
Gilly

[G-Benz]

Gillybenztech, you were right on the money!

I checked FastLane to see what a fuel pump would run, but I figured that with 31K on the odometer, it's not likely that the fuel pump would have failed this early.

Jacked up the car on Saturday and pulled the cover off. No leak occurred when the car was running until I started jiggling the whole assembly...then a trickle of gas seepage appeared near the coupling by the fuel filter(?).

Pulled the hose off and checked for damage. It was fine, so I attributed the leak to a weak hose clamp (those MB clamps sure look weird). I had several of the screw-on types in my tool rack, so the repair cost me nothing!

My wife drove the car later and said she no longer detected any fumes...so I guess the repair was successful!

Thank you all for your help on this.

Now I want to fix the driver's side seat, but I guess I'll have to wait until the top down season ends...my wife wants the SL on-line while it's sunny!

[MBenzNL]

Originally posted by G-Benz
my wife wants the SL on-line while it's sunny!

She is right...unfortunately I never had time during the last 2 winters to repair/modify mine, so now I have to settle for my mothers SLK200 whenever it is sunny and warm enough to enjoy topless driving.

greetingz,