Pictured is my original gas line and fittings from the fuel pump. Maybe a newbie question but should I re use this line or just swap it out to a rubber one?

 

If it isn't leaking, no reason to replace it. I've seen many leaks after replacement, as it's difficult to get the old nylon hose off and not damage the fittings.

 

Reuse it. It's fine

The nylon hose they sell today is junk and does this if you get alcohol (E10) anywhere near it.






The original doesn't.

 

Always replace it, those lines are not used to modern fuel.
By the way, never use E10 fuels.

 

If it's nylon, it resists ethanol. That's a big if. Nylon is a good material for carrying fuel, much better than rubber. However, it's difficult making joints, which is where rubber is preferable. I suspect that replacements fail because they aren't actually nylon. There are a whole range of 'plastics', PVC for example, that may look like nylon, but aren't and will not resist any gasoline.

Our cars have materials, mainly rubber, that don't resist ethanol. Whether we like it or not, ethanol free or low ethanol gasoline is going to be increasingly difficult to find. That doesn't have to be a disaster. When we have the opportunity or meet the necessity, we should replace items, especially rubber, with a suitable grade. It's a problem that we can overcome. When I joined a well known oil company more than 40 years ago, we had a Porsche running happily on 50% ethanol.

 

Can you explain why?

 

This statement is firstly incorrect.

Secondly in certain countries you are forced to use E10 or greater ~ or not drive. Try Brazil, parts of the US and inland in South Africa in the Sasol supply area, as examples. The split & swollen pipe I show above was on Sasol E10 & failed in 2 weeks. (sold to me as the "right stuff" from the US). Thank heavens my car is now at coast ~ no more alcohol.

Jaguar original fuel lines tolerate E10 just fine. Their later substitutes of unknown composition don't. They are provided because they look right but are junk as said before. Barratts has ceased to sell the stuff off the roll after many failures, as well as other vendors. Their made up pipes with fittings attached are OK. Their use being obvious.

Many of the black rubber fuel lines sold today by spares stores are not E10 compatible. Spares stores worth their salt will advise you which are.

If you want guaranteed compatible pipe go to your Mercedes dealer & buy the pipe designed for their E85 compatible cars or pipe from Brazil designed for 100% hydrous & anhydrous alcohol.

With the UK moving to E10 ~ compatible pipe should become more prevalent for our old Jaguars.