I did a bit of research before purchasing a replacement fuel line. The original line was marked
SAE J30 R6 SUITABLE FOR UNLEADED FUEL 5/16" It also was marked 2006 on the reverse side but I'm not sure if that refers to the year. I've owned the car since 2005 and it hasn't had a replacement hose in that time. The engine is not the original but fitted in late 2004 by the previous owner.
There are 4 significant groups of SAE codes:
1. Unmarked hose - will probably be for the original petrol formula, without modern additives (but see later comments).
2. SAE 30R6 - This is the standard for the petrol formula of 5 - 10 years ago, for fuel injection. The bore may or may not be lined with Nitrile.
3. SAE 30R7 - This is the standard for the petrol formula of 2 or 3 years ago, for fuel injection. The bore is lined with Nitrile. DIN 73379 is equivalent.
4. SAE 30R9 / SAE 30R10 - This is the current standard. The bore is lined with Fluoroelastomer/Nitrile. SAE 30R9 has Fluoroelastomer/Nitrile on the inside, while SAE 30R10 has it inside and out, which allows it to be used immersed in petrol (e.g. in a fuel tank).
There is also a marine grade for use in boats - ISO 7480 A1 - that is roughly equivalent to 30R7-and-a-bit, with added fire resistance.
I was only able to find SAE 30R9 on line. None of the local motor factors had heard of the higher spec and only a few stocked SAE 30R6 often in short fixed lengths. I need 1 metre. From what I have read the SAE 30R6 hose can tolerate small amounts of ethanol in fuel. It appears that most fuel has between 5% (e.g. Shell V-Power) and 10% (Tesco 99 Momentum). I try and stick to V-Power most of the time so I decided to use the SAE 30R6 as that was available at my local motor accessory shop. The Aeroquip Startlite SAE 30R9 nitrile line is around £25 per metre compared to the SAE 30R6 which was £4 per metre. My track car is fitted with nitrile hose as race fuel can be quite corrosive.
The slightly longer length of the new hose also meant I was able to get a more gentle radius on the bends which will hopefully mean it will last longer. The split in the old line occurred at a point where the hose was bent through an angle onto the fuel pressure regulator so that may have stressed it.
Anyway, it's good to have my Four running again now without being gassed by fuel vapour filling the interior