Petrol gushes FROM filler

[angst]

Had a strong petrol smell inside the car getting in. Took off filler cap to release vacuum (my DIY limit). Instead there was back pressure and petrol gushed out!!

A mechanic I spoke to had never come across back pressure.

Any clues? Thanks in anticipation...

 

[television]

If it was a full tank and after a quick drive it possible, yes it pressurized , and as you remove the lid if air rushes in very quickly, then it could displace some fuel

 

[kth286]

what car is it? and how many miles it done?

It will be to do with a faulty evaporative emissions system.

 

[angst]

what car is it? and how many miles it done?

It will be to do with a faulty evaporative emissions system.

Its a 260E with around 150,000 on the clock.


nb I see I have to check the forum manually as it doens't reach me by email when I select notifications!

 

[roadhog]

I get a vacuum every now and then, usually after a long drive. Guess I've got a blocked breather as well. Perhaps I just need a new filler cap?

 

[angst]

So the diagnosis seems to be that

1. The vaccum can cause back pressure forcing petrol out, if the breather tube is blocked

or

2. The system that transfers petrol fumes from the tank to the front into the engine is faulty, causing a build up of pressure in the tank.

 

[roadhog]

I've just had a look at my tank as I was in the area anyway and couldn't find a breather tube, just the filler neck. Perhaps it is time for a new filler cap for me. Doesn't explain why yours pressurises the tank though.

Are you sure it's not producing fuel? Quick, get it patented.

 

[angst]

DQUOTE=roadhog;329479]I've just had a look at my tank as I was in the area anyway and couldn't find a breather tube[/QUOTE]

I can't find one either in the crazed Haynes manual with chinese page numbering.

Can find a section on the evaporative emission control system. Doesn't say how much petrol it saves though, just blabs on about stopping hydrocarbons getting into the atmosphere so I guess it's not saving petrol, which means not much hydrocarbons are getting into the atmosphere which means it seems more like a political system.

 

[television]

The fuel tank

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=F&cat=15U&SID=47&SGR=015&SGN=01


fuel lines

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=F&cat=15U&SID=47&SGR=045&SGN=03

Closed evaporation

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=F&cat=15U&SID=47&SGR=060&SGN=04

 

[oigle]

Had a strong petrol smell inside the car getting in. Took off filler cap to release vacuum (my DIY limit). Instead there was back pressure and petrol gushed out!!

A mechanic I spoke to had never come across back pressure.

Any clues? Thanks in anticipation...

This is not uncommon, particularly if the car has been left out in the sun and heat. From your post, it seems you had left the car sitting before taking off the cap. Fuel expands and builds pressure which will not be relieved until the engine is started and the valving to the carbon canister opens. Too much pressure will relieve but low pressure will remain. When you remove the cap, if the tank is fairly full, the outflow of air will carry some fuel with it - always release cap pressure slowly. I often find pressure in the tank in Oz with our hot conditions. Tanks do not have breathers to atmosphere these days.