Think the top fuel tank seals are leaking, because whenever I fill the tank all the way up, fuel slowly leaks from the tank, problem does not arise unless I fully fill the tank.

First step flip rubber gasket inside gas cap, clear code if it returns replace sealing ring or gas cap. Leak, replace sealing rings.

 

The seals were redesigned but most likely it’s leaking from the fuel level sender unit on the driver side. The leak might be bad enough that the tank won’t hold pressure for the evap self test.

There’s a recall or warranty extension on leaky fuel tanks which would be expired on a ‘04 E320. You might check with the dealer if they’ll do a goodwill repair if you’re on good terms.

Remove the seat, remove the cover panel then check whether fuel is pooling in the pockets of sender itself or only around the lock ring. If you need a sender, get a quality unit - MB or VDO, not Uro.

If you DIY, get the fuel level to a quarter tank before you start. More than half a tank and you risk getting fuel on the upholstery PZEV tanks are different. I don’t know how to disconnect the fuel pump hoses in a PZEV tank.

Sixto
05 E320 wagon 191K miles

 

The seals were redesigned but most likely it’s leaking from the fuel level sender unit on the driver side. The leak might be bad enough that the tank won’t hold pressure for the evap self test.

There’s a recall or warranty extension on leaky fuel tanks which would be expired on a ‘04 E320. You might check with the dealer if they’ll do a goodwill repair if you’re on good terms.

Remove the seat, remove the cover panel then check whether fuel is pooling in the pockets of sender itself or only around the lock ring. If you need a sender, get a quality unit - MB or VDO, not Uro.

If you DIY, get the fuel level to a quarter tank before you start. More than half a tank and you risk getting fuel on the upholstery PZEV tanks are different. I don’t know how to disconnect the fuel pump hoses in a PZEV tank.

Sixto
05 E320 wagon 191K miles

Planning on DIY. Is it bad to drive like this for awhile? Not sure I will be able to do anything about it until December when I am on break.

 

If you can smell it, a spark can ignite it. December’s a long time from now. Can’t swing a Saturday or Labor Day?

Until then, don’t fill it beyond half tank or about 10gal. Remove the seat and cover panel to sop up the pooled fuel. That and not filling the tank beyond half should minimize fumes.

Sixto
05 E320 wagon 191K miles

 

If you can smell it, a spark can ignite it. December’s a long time from now. Can’t swing a Saturday or Labor Day?

Until then, don’t fill it beyond half tank or about 10gal. Remove the seat and cover panel to sop up the pooled fuel. That and not filling the tank beyond half should minimize fumes.

Sixto
05 E320 wagon 191K miles

Might be able to get it done... I'll order the parts in case I have time. And yeah I have not filled up past 10 gallons since I spotted the fuel leak 2 weeks ago... It was during a long drive I filled the tank and the next morning had a small puddle underneath the car and a bit of gas stuck in the skid cover in front of the rear driver side wheel. Probably was not the smartest choice I have made but drove another 4 hours without incident. I've been checking the skid cover periodically to make sure its still dry.