Hi all.As the thread is titled,pulled up outside my house earlier to the smell of fuel,then noticed it spilling from the filler neck/cap.Seems like a build up of pressure,when i slowly removed the cap it let pressure off for about 30 secs and you could hear the fuel tank contracting.

It`s just had cambelt done,could anything get knocked that would cause this??

PS Octavia VRS 2004,estate.

Thanks in advance peeps....................

On a petrol engine the fuel system is sealed so that petrol vapours are not vented to air. These vapors are stored in a canister next to the coolant expansion tank and power steering fluid reservoir. They are then released into the inlet by purge valves that are under ECU control.

The most obvious cause would be the wiring connector to the purge valve is not plugged in or loose.

Check this first.

Thanks,i`ll have a look at this.It could be,like i said the cambelts just been done,so the connector could quite easily have been dislodged....

i`ll let you know how i get on.TA MUCH.

Edited 30 September, 200817 yr by DGW
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Well,i had a wee look around the engine bay,nothing obviously wrong but theres still a lot of pressure in there,any more suggestions??

Put fuel in today and it took about 1 minute to let the pressure out!!:eek:

Remember you are working with petrol vapour!

I would let the engine go cold.

Release some but not all of the pressure at the fuel cap.

Carefully prise out the tank breather hose (the small hose) from the canister that sits between the coolant expansion tank and the power steering reservoir. If the breather hose isn't blocked then you will hear the pressure being released through the hose. Hopefully you will get this, as trying to find a blockage in the hose between the petrol tank and canister is a PITA.

Assuming the above is OK then disconnect the hose to the throttle body (larger hose) and electrical connection. Prise out the valve and see if it is jammed. If it is, try and free it and clean it.

WARNING! - if you clean it with IPA or other solvent, make sure you let it evaporate before putting the valve back. The valve feeds the throttle and injecting IPA into the engine can cause damage!!!!!!!!!!!!!!!!!!!

If it seems free then check the resistance of the valve.

If it is open circuit then replace the valve.

Double check the electrical connection to valve. To get the timing cover off, I would loosen the Coolant tank and steering reservoir and this may cause me to remove the connection to the valve.

Hope this helps

Well i dropped the car off at my mates garage as i did`nt really want to mess around with the fuel system.The fault was traced to a blockage in a breather hose.Everything seems OK now.

Thanks for the help though:thumbup::thumbup:

Glad to hear you got it fixed.

Dealing with fuel is not as dangerous as most people think, as long as you ensure that there is no ignition source (hot engine, etc) and you don't get it all over you.

i have this very same problem on my 2007 octavia vrs 2.0 tfsi can you shed any light on this?