Fuel tank’s neck

[AccidentalSeven]

Hello all,

the car is a super seven, superlight R, 2002, and this is my tank's neck.

#1 seems to be the tank's air return.  
#2 goes to the front of the car, so I'm hoping it's going into the charcoal canister.  
The problem is #3 -- what is this?  Currently, this hose goes nowhere, just hangs under the car … plugged with a screw, and is obviously leaking. 
 

Where should it go to? 
thanks,

[Croc]

 

This is a Zetec car - early 2000s - I think?  In the early days of the Zetec, Caterham repurposed the filler neck from a Rover K series which in some iterations of that engine used a low pressure fuel return line.  Somehow this extra neck connection was plumbed into the outlet from the tank with a one way valve.  I would have to look up the old K series build manuals in the Library to remember how it all plumbed together.  The Zetec does not.  As the Duratec came into the UK market they modified the neck to remove it from memory. 

 

My solution on my old maroon Zetec, which was one of the first USA press cars, was to extend the hose with a bunch of loops (so it never dripped) and just leave it open as a overflow vent.  I never had a charcoal tank vent - that neck outlet was blocked off.  Charcoal tanks came later around late 2002 onwards.

 

It should only overflow when tank is full or going hard left?

[AccidentalSeven]

Oh my… Mike, that’s a lot of knowledge!  Thank you so much!

 

Yes, this is a Zetec from 2002, and the original tank rusted and was replaced by the previous owner. When filling up, I have to go easy on the pump, or else it spills out. It seems the pump’s flow is bigger than the tank’s intake capacity.  When that happens, hose #3 fills up and slowly drips down. 
 

So if I don’t need it… First, I’ll make sure the vents are all connected right, then plug it shut.  Yet another winter project!

[Croc]

10 hours ago, AccidentalSeven said:

When filling up, I have to go easy on the pump, or else it spills out. It seems the pump’s flow is bigger than the tank’s intake capacity.  When that happens, hose #3 fills up and slowly drips down. 
 

So if I don’t need it… First, I’ll make sure the vents are all connected right, then plug it shut.  Y

 

Most Caterhams have to take it easy filling up.  I can make that happen on my Duratec car by being a klutz. 

 

You have two options:

1) You already have a neck vent so just plug this extra neck outlet at source.  If you discover that your existing neck vent is not sufficient to stop a tank vacuum then you can always unplug it and repurpose as a vent.

2) I was concerned that my tank needed more venting to prevent the vacuum effect in the tank (mine was the original Caterham tank).  So I connected a very long looping of hose (same diameter as neck outlet) and then zip tied it up high near the neck so it would partly drain back.  Any overflow in that neck outlet would then just sit in the loops and slowly evaporate.  If you still get leaks this way then that is something new to investigate on what is going on with the tank.

[pethier]

(popcorn)

[MV8]

For easier filling without back splash, I would cut and shut the tank filling vent (#2), then refit the elbow higher, into the bell and extend the tube to reach the existing hose. Then the end of the pump nozzle should extend past/ below the tank filling air vent but below the unleaded restrictor plate (if equipped).

 

The small tank vent should stay separate from the tank filling vent or a float/check valve added. Fuel rail return to the filler neck instead of the tank is common on efi retrofit, preferably with a bend inside pointing down to the tank for less aeration.

 

A 5/16 bolt long enough to have a 1/2 inch long unthreaded shank would work well (cut threads off with a hack saw) to replace the screw plugging the return hose or use a rod (bare or zinc plated steel) from the hardware store, cut to length, and radius the end to prevent cutting the inside of the hose. Most rubber barb caps are made for vacuum systems and will fail quickly is exposed to fuel, so use a short piece of fuel hose. If you reuse the existing hose, make sure it is still soft and flexible. 

[IamScotticus]

I'm actually getting away from the 90° elbow, rear fill, and going to a vertical riser below the boot cover.  Looking for options on how to do this.  A riser with a basic metal cap is sufficient.  Tank filler neck is 2.25" OD.  Need a 8" tall riser.  I have a length of fuel hose I can use, but it's very heavy and I don't want the stress on the neck.  Thinner, lighter metal pipe is better.

Yea, it's a hijack, hope OP doesn't mind.

Edited November 3 by IamScotticus

[MV8]

Post some pics of the area with the liner trim out for ideas on supporting the fill pipe (may need your own topic for that). Short as possible would be better. Modding the side filler or making a new side filler would be better still.