Have '86 560 SL (135K miles) that recently developed a persistent fuel odor in trunk. Fuel vapor expansion tank and related hoses have been replaced - tank had a small pinhole leak due to rust. Odor level dropped significantly after tank replacement but still persists - intensity varies daily. Odor becomes noticeable in passenger compartment if the hardtop is on and the vehicle is allowed to sit overnight. Fuel tank filler neck grommet was fatigued and also replaced. Fuel vapor capture system is apparently working, as fuel tank depressurizes slightly when tank filler cap is removed. Any ideas as to where the fuel odor is coming from?
Thanks in advance.

Have you check the EHA under air filter housing,I have seem leaking EHA cause this problem.

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MB STARS Master Guild Technician,12 years MB tech
6 years independent shop owner

Be sure the cap is new, not aftermarket, but OE and new...

Also, do check the fuel pump area and the EHA>


Many techs don't know this, but a halogen leak checker will find gasoline.
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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

[This message has been edited by Benzmac (edited 05-15-2000).]

I had a similar problem. I found mine by pressurizing the tank with compressed air through the expansion vent tube then listening for escaping air. Be careful not to put too much pressure in the tank or the expansion trap will "pop". My problem was a small hole in the tank that came from a sheet metal screw that held down a cover. It occured while re-installing the tank after finding another leak. Good Luck.

Jim Villers
190SL, 230SL

Had same problem with 87 420 SEL for months, then spent $5 on new gas cap, problem solved....folks at European Autoworks say it is a common problem. If cap is not completely sealing 100%, fumes back up into trunk and thence to passenger compartment...I noticed it especially with sunroof open and windows up, which created a slight vacuum in the passenger compartment at speed that would draw fumes from trunk...twice stopped and checked under hood and car for "leak"....new cap fixed it.

JoeB.