Fuel Tank Breather

[steve1506]

Hi Guys,

Got a bit confused with the pipe work for my OBP fuel tank that I have fitted so need some words of wisdom what do I do with the fuel return pipe as I am running a Pinto with twin 45s so only need the fuel feed line ,  and the same for the breather pipe 

 

Steve D

[alanrichey]

Can’t help on the return line as the my Superspec is fuel injected so uses it, but I have a very effective breather system.

There are two breather pipes, a small one (3mm) on top of the tank that deals with the day to day running, preventing a vacuum forming in the tank as you use the fuel.  In my case it simply vents into the boot area although I suppose it really ought to have some sort of valve to stop fuel coming out in the event the car is rolled.  The second is a much wider (10mm) one that goes up to the filler cap and joins the main filler tube about an inch from the cap.  This allows air to flow out of the tank during filling and allows me to use full pressure on the petrol pump rather than dribbling it in.

[Leslie Walters]

Quote

I run a pinto with a standard carb, mine had the original donor equipment on which incorporates a valve system with a return pipe to the tank, I couldn't  see any reason for this and I know this system was run without a return pipe back in the day so I removed it all, run fine for 3000 miles since, the tank is simply vented through the cap although it is a little slow to fill it doesn't cause a major issue.

 

[Sparepart]

On a normally aspirated standard sierra there is a "Fuel vapour seperator" in the pipeline from the tank to the pump, mounted not far from the pump in the engine bay. I think its there because the mechanical pump is sucking fuel out of the tank at the other end of the car, so the pulsing drops in pressure between the pump and the tank can lead to small pockets of vapour to be created, especially in hot climates. The seperator "vents" any pockets back to the fuel tank. Home central heating systems can have something similar to automatically bleed air the builds up, the "return" pipe runs back up to the header tank. Anyway, I digress, on my car I did away with the vapour seperator and the return pipe. I did connect a hose to the connector that was used by the return pipe on the top of the tank, next to the pick up pipe. The hose just runs up to a level as high as the top of the fuel filter and vents to air, Like Alan Richy I should put a non return valve in here in case the car rolls.

[steve1506]

Gents thanks for your replies I  have ordered 2 valves and will fit as suggested on the ends of the extended pipes

 

steve D