6 replies to this topic

[Parrella]

I am a little puzzled and was hoping someone can help clarify. I have been re-building a clubman and trying to put the fuel tanks, lines etc all back together that i had removed over 5 years ago. I have two fuel lines that i have labelled, one being fuel supply and the other labelled fuel return.

 

I am unsure how the fuel return line works and where it is to be connected up to or if it is even required. 

 

The car used to have a 998cc engine and as part of the rebuild i have put in a 1275 and also added a RH fuel tank. Off memory the original 998 had a mechanical fuel pump and the 1275 that i purchased was running an electric pump so i will need to purchase one shortly. My understanding is the fuel lines will run from the tanks into the fuel pump via a filter and then from the fuel pump directly to the Carbies. I believe the carbies have a fuel overflow or return line that can either be left open for excess fuel or plumbed back via return lines however this is the part i am unsure of. 

 

Can anyone help either with diagram, photos or explaining how its all connected. 

 

Thanks in advance for any help, happy to put up photos if that helps 

[GraemeC]

The only Minis that had a fuel return line were the injection ones.

The overflow from the carb should just be piped so it vents clear of the exhaust and the fuel would drop out under the car, it is not plumbed back into anywhere.

[Bat]

Hi,

I'm guessing you're in Australia?

Do you have an emissions system fitted that collects fuel vapour?

If so you may have the vent pipe from the carb and the tank piped to a canister?

Cheers 

[Parrella]

thank you all for the replies;

 

Yeah I'm in Australia. Not sure about if we have an emissions system fitted or not; is there an easy way to find out? what would said container look like?

 

Kinda out of my depth when it comes to these kinds of issues; really trying to piece the whole engine bay and everything related back together based on photos, video's and common sense however there are so many different subtle variations to the engine bay configurations that Its made it difficult to know if I'm on the right track.

[Bat]

Hi,

That I don't know as we never had anything like that I cthe UK until injection cars and along.

Moke Spider is from NSW, he may know...

Cheers    

[timmy850]

The emissions spec cars had a charcoal canister in the engine bay to trap the fuel vapours. The vent line from the tank meets the charcoal canister and it then vents to the intake under certain conditions. 

 

If you don't have any of the emissions gear under the bonnet you can vent from the top of the tank to the floor under the boot of the car like the earlier cars. 

 

Technically you should still be meeting all the ADR regulations listed on your build plate, including the emissions ones..

[Spider]

The Vapor Return was introduced in 1976 and that had the Charcoal Canister along with the return line to the fuel tank. Since the advent of 'forced' use of unleaded fuels, this system in now redundant and you no longer require it for Rego. I no longer have it on any of my cars and they have all been for Blue Slip at one time or another over the past 10 years, the last a 1978 Clubbie also with a 1275, electric fuel pump and twin tanks, only last week and of course, this car did originally have the system.

 

These systems were fitted to deal with the Photo-chemical smog that could be seen hanging over most capital cities, it usually appeared as a brown or orange haze, and was worse with elevated temps (perhaps why it wasn't fitted in the UK?). The chemical(s) that were present in petrol of the era that caused this are no longer used in unleaded fuels.

 

If I recall, ADR 27 and ADR 27A, which these Vapor Return Systems needed to meet, have been repealed, though, don't take that as gospel.

 

If you are still keen to connect it for originality, there was two types, depending on the year. The easiest way to ID the system is to look at the Charcoal Canister (which were supposed to be routinely replaced about every 20 000 km, but I don't know anyone who ever did!) and see how many fittings for lines are on it, there was a 2 and a 3 line type, though, for the most part, they connected up similar.

 

2 line system;-

 

 

3 line system;-

 

 

(The inset shows the Van which was exempt at the time the 2 line system was introduced)

 

 

I'd suggest given what you are doing in setting up the car, to ignore these systems.

 

Just coming back to your proposed installation, if you are using an SU or similar Coil & Diaphragm type pump, I would suggest you install the filter after the pump and not before it. If installed on the inlet side and the filter blocks, the pump will stall in an energised state and burn out. The pumps are designed to allow some 'stuff' to flow through them and have a mesh filter for anything bigger than they can withstand.

 

If you examine the diagrams above, although they both use mechanical pumps, they do show the filter after the pump and for a similar reason, though, there's nothing to burn out with these, the pumps will still 'stall', it leaves the pump leaver 'suspended' and they they are hammered until the pump breaks and usually the bits fall in the gearbox.