was connecting up some of the more fiddily pipework on my fuel filler neck and noticed that one of the breather pipes runs along the floorpan of the car into the engine bay and is just open, looked at the diagram below and have found that it used to connected to the charcoal canister which i dont have any more. So my question is if i have no charcoal canister can i remove the gravity valve (12) and all the associated pipework (9-10-15-13). also just out of curiosity what did the gravity valve and charoal system do?
The breather will obviously allow the tank to breath - e.g as the petrol vapourises and/or expands with temperature. I presume from the description that the the gravity valve will only allow the tank to breath under 'normal' conditions, but close preventing spillage if, for instance, the car is on it's roof.
The carbon canister is some hippie invention to protect "mother earth". Sod it off at the earliest convenience.
I'd definitely keep the gravity valve, but you could shorten the breather hose as you see fit. I've found the fuel cap makes more of a difference with the tank breathing that the breather hose anyway, but then my gravity may be stuck closed or something.
When I got the car the tank didn't breath at all. After long journeys you could undo the fuel cap and a great whoosh of air would come in and you could hear the tank reshaping! This was backed up when removing the in-tank pump, the whole mechanism was bent to about 30 degrees from normal :o
Are you talking about the purge valve in the engine bay that controls the release of vapour from the canister into the engine? You can bin that when removing the canister
i forgot to post the picture i was talking about the gravity valve is number 12, was thinking i could do away with it as i thought it was only there for use with the charcoal canister, but i now see that it is a saftey thing so that when the car is in a crash or upside down no fuel vapour is relased. just having a bit of a nighmare trying to refit all the pipes cant find any hose clamps small enough and its rather fiddly working inside the rear quater! will be going to vw tommorw and ordering some smallerr clamps but im hoping there not the type you need a special tool to use!! (http://i673.photobucket.com/albums/vv92/antywill666/fuelbreathingschematic.png)