Injection fuel tank pipes

[Anthony]

I would be grateful for a little guidance please.

 

I am looking to fit a flush fuel filler cap to an injection set up. To progress a reliable solution, I would like to fully understand the connections. My understanding as follows ;-

 

1. Connection on the middle of the tank under boot floor - pipe goes to one way valve / or is this the return pipe ?

 

2. large appeture/pipe - fuel filler pipe

 

3. Small dia pipe next to large dia pipe ( above no.2) normally connects into a "black" metal connector which in turn connects to the fuel filler

 

4. Fuel pump output on side of tank which feeds to carbs

 

Apologies for the dumb questions which I suspect would be straight forward with a K-series build manual, but I am converting from a carb based chassis and I have no terms of reference

 

Many thanks inadvance

 

Anthony

 

No engine, but 4 wheels...

 

 

 

 

[F355GTS]

1) Vent

 

2) Yes

 

3) Mine is joined with a short hose to the appropriate pipe on the bottom of the filler neck

 

4) Yes

 

Fuel return is on front of tank near top slightly off centre to the left

 

Mark

[Grim Reaper]

I think No1 is the return from the fuel pressure regulator?? Does it change from rubber hose on the tank to plastic pipe somewhere under the boot floor..if it does,it is.

No 2 is the Filler hose via the check flap fitting (in place to ensure only unleaded filler nozzle fits)

No 3 is the vent from the tank to aid filling

No 4 is the fuel pump outlet to injection

There is another pipe connection on the check flap fitting which is the vent for when the filler cap is in place to allow air to feed in to the tank as fuel level drops so as not to create a vacuum.

I however stand to be corrected!

[Anthony]

Guys, if pipe 3 the vent near the main fuel filler pipe was connected to a one way valve - ie air can get in but fuel cannot get out would that work ?

 

I am looking to avoid having a a joint between the filler pipe and the vent pipe

 

Anthony

 

No engine, but 4 wheels...

 

 

 

 

[Grim Reaper]

No,the idea (as far as I can tell) of the large vent is to allow air to escape from the tank as it is filled up fast with fuel from the petrol station pump,it vents into the filler neck so that any fuel that gets up it can go back into the tank but not spill out via the filler.

You could put a one way valve on it (from inside to outside) but it may have the effect of causing restriction to how fast you can fill the tank up.

On the other hand,if you have no other vent point on the filler/tank, a one way valve from outside to inside would suffice in this pipe outlet (3) and as before,you would have to be careful how fast you fill up.

It doesn't matter if you get positive pressure in the tank (up to a point) but a partial vacuum will kill the engine and cause lots of head scratching .

Clear as Mud??

Actually,reading the posts over again and recalling another vent pipe on the tank I may have misled you...is there a vent near the fuel level sender?

The return pipe (as Mark said) connects to the front top edge of the tank under the boot floor (wooden bit),the other vent would be under the honeycombed bit and will be connected to the unleaded fuel only bit on my car,then another vent from there down the side of the tank to the right rear corner.

I wish I had taken some photo's of it now.

 

Edited by - Grim Reaper on 11 Apr 2003 13:39:38

[felix.klauser]

When I converted to injection I had a fabricator cut out the standard Caterham filler neck and the related pipes. A new filler was welded in place further inboard to give a better angle to the petrol pump nozzle. I don't have any breather or vent fittings; my vent is a tiny hole, approximately 1mm in diameter, under the flip-up lever of the flush fuel filler. Probably not ideal if the car overturns but I don't plan oin being in it for long after that happens.

[Trevor Phillips]

Anthony,

Have you included a roll-over 1 way valve in the scheme.

 

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