Fuelling problem

Q

I have a 2013 Mercedes A-class 220 CDI auto. I have had this vehicle for a couple years now and have had no problems till recently. I have been having issues putting diesel into the tank at the fuel stations where I’ve only been lucky to get half a litre before it spits fuel out of the filler pipe. The fuel does not go down into the fuel tank but sits in the filler pipe – it seems to take hours before fuel drains into the tank. This problem has only started in the past month and I have had no issues before this putting fuel in it.

Now I can only get a small amount of diesel in by using a small jerry can, even then I can only get fuel into the filler neck and wait few hours before I can get some more in at a later time.

I put a long pipe to down the filler neck to see for any blockages and it seems OK. I have tried the pipe and pouring fuel down at the same time still no difference. There must be a problem with the vent pipes?

I read on forums that there is a valve that controls this on some diesel Mercedes. I’ve been in touch with a Mercedes dealer to confirm if there is some sort of valve and they did not know.

I have booked my car into an independent Mercedes garage to look at it but that’s three weeks away. Any help on this would be appreciated.

Steve Sunderland

A

The fuel filler on your Mercedes A-class, unlike the earlier version, does not have a separate breather pipe running in tandem with the filler pipe. But even if the breather were blocked, I would not expect the fuel to sit in the filler neck and should still enter the tank. This may possibly create a few bubbles or gulps back up the system but filling slowly should result in the fuel getting in the tank.

Although you have mentioned that you have a used a long pipe to run down the filler neck, the filler tube on your Mercedes is long with two sharp bends, and it may be possible that you are not reaching the tank.

Presuming that the tank is not full, and the gauge is faulty, then I suspect that the problem may be that an object in the tank has dislodged and has blocked the filler neck – this may be a section of baffle plate from the tank.

Although this would be very rare, the symptoms you describe are very rare, and whilst the filling of the tank can at sometimes become time-consuming due to a venting problem, it is unlikely that such a problem could cause such an extreme condition as you now have.

The answer will be to remove the filler neck at the tank, and then investigate – hopefully at this stage the cause of the problem will become apparent.