There is a tremendous rush of air into the fuel tank when I remove the filler cap. Whether I'm filling up from an empty tank of half a tank, I break a strong vacuum (sounds like a terrible health problem). Is there some vent I should check or is it normal for the fuel tank to suck in rodents and small pets?

As a side note, I have a nagging rough idle but it accelerates and cruises like a dream.

Thanks,
Sixto
91 300SE

Yes, the pressure in the fuel tank is normal. Mine does the same thing. I believe the gas tanks work somehow by being pressurized.

As for you rough idle, mine idled crappy, but drove like a dream too. It turned out to be the fuel filter. Check for the last time it was replaced on your car. Check spark plugs also. GOod luck!

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

The former 1985 300SL of my mother had the same need of air as soon as the filler cap got removed. The tank of my 1990 300SL has a smaller need of air. The vacuum in the tank of the 1990 300SL is not half as big as with the 1985 300SL...Both cars run great and I never figured the vacuum in the 1985 300SL tank to be a problem.

greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)