Slow Fuel Fill and Foaming on CDI
Thread Starter
Super Member
Joined: Jun 2004
Posts: 996
Likes: 16
From: Tampa, Florida
2017 E300W
Slow Fuel Fill and Foaming on CDI
Went to fill up today and diesel barely trickled in, lots of foaming, and it sounded like it was gargling! Fuel bubbled up to the top of the filler tube and slowly trickled to the tank. Took about 15 min. for 12 gal. Any thoughts on the problem? Is there some sort of valve between the filler tube and the tank?
Last edited by TPAbnz; Sep 26, 2010 at 07:47 PM.
Newbie
Joined: Sep 2007
Posts: 12
Likes: 0
2005 E 220 CDI
Just want to chime in saying I have the same problem. From time to time it is very hard to put diesel in the tank. Sometimes I just have to give up, driving away from the pump having only managed to fill about 10-20 liters (3-6 us gal). The problem does seem to be that the diesel is foaming. This happens in very low ambient temperatures as well as warm weather. What could be causing this?
220 cdi wagon
220 cdi wagon
Senior Member
Joined: Feb 2010
Posts: 431
Likes: 4
From: Cross Roads, PA
2008 ML320CDI
Personally I would relate it to the pump. They could have changed filters on the pump and there was an air leak, so in essence you were pumping foam instead of fuel. Next time this happens try a different pump or station just as a test.
Junior Member
Joined: Jan 2008
Posts: 16
Likes: 0
From: Kentucky
'06 E320 CDI, NAV/HK Sound/Xenons/KeylessGo, '05 997 Carrera cabrio, '08 R320 CDI.
Same issue- slow fill and overflow fueling up.
I had the same problem today filling up my '06 E320 CDI and was unable to get a full tank of fuel in, I was in a hurry so I left after an incomplete fill (~12 gallons took me forever, with multiple interruptions), and closer to home went to another gas station where I was able to fill without any problems whatsoever (felt relieved that it was not a problem with my tank/fuel sensor etc). I believe theres a filter (???charcoal filter) leading to the fuel tank that backs up when the fuel is foamy. The simple solution is to fill at another pump. 
