Scary Fuel issue

[Rikki Kitto]

Bit of a scare the other day geezer came up to me in traffic said you're leaking petrol mate, I pulled over and sure enough petrol was literally pouring out of the filler cap, didn't tighten it up but surely it shouldn't do this

It now seems to be building up loads of pressure whilst engine is running to the point where the filler cap is being pushed out of the flap, It has done this in the past but not to this level, I sometimes just leave the cap slightly undone to help release the pressure but now this is happening suppose I better get it sorted, any ideas

[Rusty]

Potentially, sounds like the blue N80 solenoid under the inlet manifold has gone kaput, so you're getting boost in to the breather system for the fuel tank.

Block it off at the inlet and breather and see if it still does the same. Best not to run it like that for any more than a test run though.

[Rikki Kitto]

Not good seeing fuel literally pumping out of the filler onto the floor, I'll check it later thanks

[Rusty]

Did you have your fuel pump upgraded for the new power levels? Might be something's come loose inside the tank?

[Rikki Kitto]

Yeh fitted an 044 no issue in the boot though, literally pushing fuel out of the filler cap if left not tight but when tight just crates loads of pressure. It has done this for a while but not this bad maybe the new pump is now showing an earlier problem up a lot more

[UrS4boy]

N80 Evaporative Emissions Frequency Control Valve and Canister info

Potentially, sounds like the blue N80 solenoid under the inlet manifold has gone kaput, so you're getting boost in to the breather system for the fuel tank. Block it off at the inlet and breather and see if it still does the same. Best not to run it like that for any more than a test run though.

Agree with the possibility. Since the evaporative emissions line at the top of the fuel tank does not extend down into the tank (it just wants fuel vapours not liquid), the problem would be exacerbated by over filling the tank, i.e. filling into the neck of the tank. Even with the N80 failure this should not happen when the fuel level drops.

But it is still likely an N80 Failure.

N80 Evaporative Emissions Frequency Control Valve and Canister info:

http://forums.quattroworld.com/s4s6/msgs/21014.phtml

[Rikki Kitto]

Great help as always, I only fill the tank 2/3 full unless going on long trip this has been happening even when on last 1/4 tank

[Cottis]

Not smoking = Result!

[UrS4boy]

Great help as always, I only fill the tank 2/3 full unless going on long trip this has been happening even when on last 1/4 tank

How many hoses extend down into your fuel tank. There should only be 2. If there is three, somebody incorrectly extended the evaporative emissions pick-up hose. (IMO)

[Trist28]

After an S2 Avant of mine had a complete rear 1/4 (inner & outer) fitted. They refitted the rear tank and sub frame - then fuel lines. They got the 3 fuel pipes mixed up and it did exactly the same - pumped fuel out of the breather pipe at the top of the filler pipe. Fuel also started coming out of the carbon canister/front wing.

Would take around 10 miles before you could smell fuel, see leaks etc

[Rikki Kitto]

Busy with work for the next couple of weeks so will have to wait but that's the next job fir sure

[Rikki Kitto]

After an S2 Avant of mine had a complete rear 1/4 (inner & outer) fitted. They refitted the rear tank and sub frame - then fuel lines. They got the 3 fuel pipes mixed up and it did exactly the same - pumped fuel out of the breather pipe at the top of the filler pipe. Fuel also started coming out of the carbon canister/front wing.

Would take around 10 miles before you could smell fuel, see leaks etc

Mine looks as though the tank itself is filling with pressure and pushing the fuel up and out the filler tube