Return fuel pipes?

Hi all

I know the fuel feed to the pump needs to be 8mm but can i also use 8mm for the return line to?

It should be 6mm but i can't see why i can't use 8mm unless it needs 6mm for back pressure or something i don't understand.

I just think it would be easier to do the lot the same.


Cheers landy lee

landy-lee said:

Hi all

I know the fuel feed to the pump needs to be 8mm but can i also use 8mm for the return line to?

It should be 6mm but i can't see why i can't use 8mm unless it needs 6mm for back pressure or something i don't understand.

I just think it would be easier to do the lot the same.


Cheers landy lee

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I would check your sizes as 8mm sounds small to me?

As a general rule flex hose (ie rubber) is measured id internally, rigid pipe incl nylon is measured od externally.

lynall said:

I would check your sizes as 8mm sounds small to me?

As a general rule flex hose (ie rubber) is measured id internally, rigid pipe incl nylon is measured od externally.

Click to expand...

My 300tdi had 8mm id feed and 6mm id return

Think There is a restriction some where. It’s in 1 of the fitting.

landy-lee said:

My 300tdi had 8mm id feed and 6mm id return

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I kind of gathered that, as usual I badly worded my reply, what I was getting at is that if you buy nylon 8mm pipe it will be 8mm outside dia and 5 to 6mm inside dia.
So I would guess that what you need is 10mm od nylon pipe with a wall thickness of 1.5mm leaving you 7mm id making it a nice snug fit onto the 8mm barbed tails.

Hicap phill said:

Think There is a restriction some where. It’s in 1 of the fitting.

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Its in the fip return banjo, Iirc it keeps the fip pressure at 70psi, madly that one banjo is the best part of 40 quid!

lynall said:

Its in the fip return banjo, Iirc it keeps the fip pressure at 70psi, madly that one banjo is the best part of 40 quid!

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Arrr ok so i believe using the same pipe for feed and return will be ok as the banjo has a pressure valve type thingy in it.

Cheers mate every day is a school day!

landy-lee said:

Arrr ok so i believe using the same pipe for feed and return will be ok as the banjo has a pressure valve type thingy in it.

Cheers mate every day is a school day!

Click to expand...

I only learnt about the banjo a few years ago, also learnt you can actually adjust that pressure in the pump itself, something I mean to do one day maybe possibly!