Car is 1997 E320. I usually buy my gasoline at the same station which has many sets of pumps. The past two or three fills have presented a problem. The pumps shut off after only a small amount of gas has been pumped. Removal of the nozzle shows that there is a pressure build-up in the tank. I can then start the pump again and the same thing happens. Eventually, I can get the tank mostly filled. Isn't there supposed to be some way for the air in the empty tank to escape as you fill it? I assume it would be some part of a closed system so that gasoline vapors are captured? Could I have a valve/solenoid that is not opening when I turn off the ignition? How does the closed system function differently with engine running and not running? Car is running fine as far as I can tell. Thanks.

There is a small hole/vent about 2 to 3cm back from the tip of the fuel nozzle on any gas pump...while you fill your car, the air/vapours escape through this opening...as your tank fills, the oil level will rise beyond the hole, at which point no air is escaping, causing the pump to shut off/click...I always associated the pump shutting off prematurely as something bein' wrong with the pump itself, or I did not have the nozzle properly inserted...but obviously, if it is consistently doin' it at various pumps, there may be something more serious (hopefully, it is not with your car)...may I suggest tryin' another station, or bringing up the problem with the manager of the station you frequent? They are usually very willing to help out regular customers...

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1995 black pearl/black Mercedes-Benz E420 :

Most 1997 & later cars have OBVR (on-board vapor recovery) systems. IF your filler has a metal insert with an o-ring where the gas nozzle goes into the neck then you car has that system.
If you have a "plastic" door in the filler neck then your car doesn't have OBVR.
OBVR systems have had some problems with filling the tank & should be looked at by an expert!

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