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Have removed the fuel lines under hood, there are 4 combination rubber/steel lines and a rubber return line going from fuel cooler to firewall.
can someone confirm actual size? As per my search on here these are said to be 5/16” and 3/8”, this is not the case.
5/16” is slightly large as is 3/8”
measured with calliper, compared factory hose to new, even went to hydraulic shop to see if they could rebuild(local shop wouldn't do it as they don't have a supplier for this hose). The barbs are not 5/16 and 3/8, seem to be slightly smaller.
Due to fire risk, i dont want to mess around with close fit, needs to be exact.
I figured it out, factory uses 7mm and 8.5mm hose.
3/8 and 5/16 is not correct. Dont know why these sizes keep getting referenced
It will be because much of the ownership knowledge shared online about XJS's is from USA, where I assume those imperial hose measurements are fairly standard and 'close enough'
I used 8mm Cohline 2240 hose for all the injector stubs etc, & from memory a slightly larger one on the firewall connections. Was more expensive than generic fuel hose but using a high quality pliable ethanol proof hose makes all the difference. It fit easily & still all looks like new 5 years later.
Can't beat the Cohline - I use it too - that and Gates Barricade - fuel hose is not something you should scrimp on, that is a T shirt I got on my Sabre - the hose turned out to be fake 'R9' and was rotten and leaking in less than 2 years - thank heaven for the sense of smell ....
I don't know if it's available in metric but I recently learned that marine rated fuel line is incredibly tuff stuff, like rated to survive things like an open flame for a given time tuff and has lower permeability than regular low permeability automotive stuff. Apparently the engine room of a boat
is even less of a place to skimp on fuel lines than a car. It's all pretty well documented online, the US coast guard has specs for it,
I'd assume similar organizations in other countries do as well. I plumbed my lump'd under hood lines with it and one of the rear trunk lines, wish I'd known about it sooner before I'd already done the rest.
The extremely low permeability is probly a bigger bonus for the trunk lines than the under hood stuff for us.
Far as metric fuel hose you can order it, anywhere that deals in european car parts should have it by the foot in the usual sizes. Call pelicanparts or autohausaz if nothing else though I've had prices buying it on ebay in small bulks tbh.
FWIW I've used 5/16" and 3/8" hose on many older Jags with no problems
Cheers
DD
Those sizes are too large for my 86, could probably make it work with clamps but I’m not risking it. Factory barbs are designed for 7mm and 8.5mm ID hose.
Far as metric fuel hose you can order it, anywhere that deals in european car parts should have it by the foot in the usual sizes. Call pelicanparts or autohausaz if nothing else though I've had prices buying it on ebay in small bulks tbh.
neither Pelican nor Autohauosaz carries the required 8.5mm, the 7mm they have.
I don't know if it's available in metric but I recently learned that marine rated fuel line is incredibly tuff stuff, like rated to survive things like an open flame for a given time tuff and has lower permeability than regular low permeability automotive stuff. Apparently the engine room of a boat
I have successfully used 3/8 and 5/16 hoses without a problem. For my fuel injector hose I used 5/16 hose on the barbed fittings for the injector and fuel rail without the use of clamps. I used new ferrules.
On the fuel supply line, I used a barbed reducer 3/8 to 5/16. the barbed reducer I purchased is 1 1/4 inch long and has 4 barbs on each end. I have no leaks to date that is 3 years and counting. I am using Marine grade hoses throughout my car I had to exert a lot of force to install said hoses.
I also tried for a long time to try and purchase the Metric sized hoses to no avail, then Doug recommended that I try the Marine grade hoses and I have no regrets.
My 2 cents>>>> go for the 5/16 and 3/8 marine grade hoses.
8.5mm ID hose - Cohline 2134.0209
available via many vendors online(mercedes spec hose)
7mm ID hose - i dont know the manufacturer or part number yet, will know when it arrives. This is a common size for classic VW, the VW vendors sell this modern(non braided) hose.
both are safe for injection and modern fuels.
no excuse to use different sizes as these are available.
Need confirmation of under hood fuel line size
It's all pretty well documented online, the US coast guard has specs for it, 
