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fuel breather pipe

PostPosted: Tue Aug 23, 2005 4:10 pm
by phatmendus
One more question to add to the list... where the fuel tank breather pipe goes behind the headlining does anyone know what holes the pipe feeds through on either side of the car. There are 2 holes with rubber inserts in them on the back of the air vent moulding, are these the holes the pipe should run through? If so why are there 2 on each side?



Re: fuel breather pipe

PostPosted: Wed Aug 24, 2005 2:55 am
by berni29
Hi Simon

They usually exit inboard a bit before the rear wheel. One each side. If yours are connected to the side air vents then it sounds like a bad idea! There are a couple of modifications that people make (not heard of yours before) usually involving some way of venting to the filler neck. Look up previous posts on the subject.......

breather system

PostPosted: Wed Aug 24, 2005 10:04 am
by phatmendus
Thanks for the advise. Basically my fuel tank breather system is a copy from a club lotus magazine where i have the pipe coming from both sides of the tank (top of) with the pipes joining in the middle. This then has two branches. One off to the filler cap as you say, and another branch
being routed where the original used to go. The problem is I didnt take out the original so im not too sure how or where it went, all I have been told is that it ran between the headlining and the roof, and then somehow gets fed to the bottom of the car (to atmosphere) Is this correct as my headlining is being done as I write this.



Re: fuel breather pipe

PostPosted: Wed Aug 24, 2005 4:32 pm
by chrishewett
The pipes originally come from the top of the tank either side and run up and through the headlining, crossing at the top and then go down the opposite side they started from and out through the bottom of the car so that your expensive fuel can evaporate away in the garage!
The spyder system, that I think is the best, is for the pipe on the filler side to be capped off and the offside pipe to remain going through the headlining but then to connect to the filler via the modified filler tube. Since fitting this I have had no problem with fuel evaporation or filling.
If you are replacing your headlining I would make sure you have the appropriate pipe going through first as you wont be able to route it after.

Re: fuel breather pipe

PostPosted: Thu Aug 25, 2005 9:18 am
by zuckerlowe
Hi guys,
why does it go over the headlining in the first place? I rerouted mine up just below the rear window and the down through the floor as normal. Am I missing something?

Steve (1968 +2)

Re: fuel breather pipe

PostPosted: Thu Aug 25, 2005 12:49 pm
by chrishewett
I suppose that if you had a brimming tank and were doing some hard cornering you may get fuel in the pipe. I couldn't see any point in changing the route of the pipe when I modified mine.

Re: fuel breather pipe

PostPosted: Thu Aug 25, 2005 4:09 pm
by john.p.clegg
I think it is the case of if you roll it and it ends up upside down the fuel will stay in the tank as the breathers are higher than the tank????

Re: fuel breather pipe

PostPosted: Wed Aug 31, 2005 2:01 am
by 72plus2
Check this out...

My car (Federal +2s130m mfg'd Dec '71) has a modified breather that sounds like the spyder system described in another post on this thread, however the vent from the filler side connects directly to the filler neck - no crossing over from the other side of the car. If this is a modification, I did not perform it d, a PO did.

However, my tank does not have two breather tubes exiting each side of the tank. Rather, there is the one side vent tube I described in the previous paragraph, and another smaller vent tube exiting the top of the tank. This top vent is connected to an auxilary canister (evaporative??) that mounted on the rear of the petrol tank.

I suspect this set up is a mixture of stock and PO modifications, as I have found the crossing-over-the-headlining vent tubes described in earlier posts behind the air extractor grilles, and exiting underneath the car in the correct location. Perhaps the federal cars, or cars manufactured after a certain date have the evaporative canister with the top vent? BTW, the cross over system is illustrated quite clearly in the repair manual.

I have a horrible smell of petrol in the car. It is so bad that the windows are constantly covered with a mucky film that is a real bugger to get off. I am going to replace the flexable joins on the filler neck and vent pipe. If that doen not fix the problem I guess I will have to check the tank drain plug then the fuel line. Any suggestions?

Last thing... do modern cars have vented fuel tanks?



Re: fuel breather pipe

PostPosted: Wed Aug 31, 2005 12:22 pm
by M100
>do modern cars have vented fuel tanks

Yes, but but not to atmosphere. They vent into a charcoal cannister that is then purged to the inlet manifold when driving along at speed.