WHY does the pump nozzle shut off after 6 gallons?
 

I have read somewhere this has to do with a clogged vent. I do not have my Haynes handy, but this is ONLY a problem when it's less than half full when I fill up (i.e., when vapors accumulate - I presume)

Also worse when warmer outside.

This is driving me nuts

I only experience that on certain pumps.
Blame it on a " hyper-sensitive " nozzle.
How many pumps ( stations ) have you tried?

Every pump I've been to for the last 2 years or so, with the exception of one, which actually DIDN'T shut off and made a mess (but that was a 40* day)

When it shuts off, I can hear the gas bubbling down into the tank for a few secs. Then I start the pump again, same cycle occurs. Gasses are clearly building up in the filler neck. Is there some kind of vent line I need to clean? Could be blocked?

Are you sure it's not a faulty gauge or sending unit? (Are you really that low?)

Gerry

Not sure about vapourpressure built-up.
Given the fact that we have 2 tanks, maybe there is a problem with them not equalizing?

Not a gauge
 

If I drive 350 miles and hit the first white line and the nozzle doesn't work, I put in 12.5 gallons. If the light is on, 14. I'm not that clueless!

Manny, I did not know we had 2 tanks. Where have I been? Is one a reserve? How much does it hold? I thought it was 1 16.5 gallon tank

to be fair.....
 

I suppose one could think it was my sending unit, but we are talking about any time the tank is below half full. It can be to the fuel light, and shuts off after 6-8 gallons. That means half the tank at that point is vapor. I have to manually squeeze the pump to a trickle for the remaining 6-8 gallons. That is not normal

Have a look under your car, when it gets warmer outside. :D
That's why there are " left " & " right " fuelsenders.
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1XC0ZKQX91Z40QB4GV&year=2000&make=MB&model=C-230-002&category=E&part=Fuel+Level+Sending+Unit
The " reserve " is part of the whole system.
This is what the tank looks like:
http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=202085&M=111%2E975&GA=722%2E605&GM=717%2E460&CT=&cat=45H&SID=47&SGR=015&SGN=01