[s-cars] fuel vapor on warm days . . .

[Rbade12 at aol.com]

In a message dated 4/5/2004 12:32:56 PM Central Standard Time, 
mark.pollan at mci.com writes:
Has not happened to me but...Fuel filler cap perhaps?

My 91 200 20v is doing the same thing, fuel vapor from the right rear wheel 
well, more pronounced the warmer it is. When I unscrew the gas cap there is 
pressure built up behind it, again, more pronounced the warmer it is, is this 
normal? My other vehicles don't do it.
Looking in Bentley there is reference to a carbon cannister frequency valve, 
is this the check valve refered to earlier or is there another elsewhere?

Thanks,  Bob      Franklin, WI