Fuel hose replacement
Discussion
An examination of the fuel hoses in the engine bay revealed that they're just starting to show tiny external cracks, so looks like replacement time. Fuel filter could probably do with replacing as well, so thought I might as well do undercar lines while I'm at it.
Unfortunately the Steve Heath book turns out to be of no help with this job so I'm hoping I can get some pointers from someone who's done it.
From what I can see, it looks like there's a length of 8mm bore hose going from the fuel filter to what looks like 8mm copper nickel pipe that then tuns forwards along the chassis and I'm guessing up into the engine bay behind the engine from where another length of hose then joins to the fuel rail on the engine.
There's also some rubber hose running along the chassis which runs with the above pipe part of the way and ultimately runs through the body above the outlet pipe from the tank to the pump. Does anybody know what this hose is? And does that need replacing?
It looks like there's a return hose from the fuel rail that connects to another hard pipe that runs down the driver's side and ends under the axle, from where another length of hose runs back and through a hole in the body that's just sealed with silicone. Is this rear piece of hose usually replaced?
Unfortunately the Steve Heath book turns out to be of no help with this job so I'm hoping I can get some pointers from someone who's done it.
From what I can see, it looks like there's a length of 8mm bore hose going from the fuel filter to what looks like 8mm copper nickel pipe that then tuns forwards along the chassis and I'm guessing up into the engine bay behind the engine from where another length of hose then joins to the fuel rail on the engine.
There's also some rubber hose running along the chassis which runs with the above pipe part of the way and ultimately runs through the body above the outlet pipe from the tank to the pump. Does anybody know what this hose is? And does that need replacing?
It looks like there's a return hose from the fuel rail that connects to another hard pipe that runs down the driver's side and ends under the axle, from where another length of hose runs back and through a hole in the body that's just sealed with silicone. Is this rear piece of hose usually replaced?
Better to do it all but you will need to ease the fuel tank back to get to the return line, not a difficult job though.
The outlet from the tank is awkward but not impossible and we'll worth doing, the silicone will be covering the hack job Tvr did to the hole in the body which looked like it had been cut with an axe on mine!
The outlet from the tank is awkward but not impossible and we'll worth doing, the silicone will be covering the hack job Tvr did to the hole in the body which looked like it had been cut with an axe on mine!
Just done mine.
Worth buying some better fuel clips while you're ordering your fuel hose. As you've discovered you want an 8mm internal hose I found SAE J9 was the spec for modern fuels and the clips you need will be for a 13mm(ish) outside diameter.
grahambell said:
There's also some rubber hose running along the chassis which runs with the above pipe part of the way and ultimately runs through the body above the outlet pipe from the tank to the pump. Does anybody know what this hose is? And does that need replacing?
This is the breather that comes from the plenum through the carbon can and back to the cap on the image on the link you've been given.grahambell said:
It looks like there's a return hose from the fuel rail that connects to another hard pipe that runs down the driver's side and ends under the axle, from where another length of hose runs back and through a hole in the body that's just sealed with silicone. Is this rear piece of hose usually replaced?
Most of this on mine was a hard line. Just from the top rear of the tank to the chassis needed doing. You can get to the tank connector without much trouble just remove the top piece of carpet and you'll see a pipe pointing back towards the drivers seat coming out. I fed the hose in through the bottom and used a long grabber to pull the hose up. For me the easiest piece to replace.Worth buying some better fuel clips while you're ordering your fuel hose. As you've discovered you want an 8mm internal hose I found SAE J9 was the spec for modern fuels and the clips you need will be for a 13mm(ish) outside diameter.
First job - Cut yourself a hole in the shelf behind the seats and fit a 5" boat hatch. You'll thank me later... It makes a near impossible of replacing the fuel filter almost easy.
Also this is what a Chimaera fuel filter looks like after 60K miles... I don't think it was ever replaced, even though the car was supposedly serviced many times by a well known specialist....
Also this is what a Chimaera fuel filter looks like after 60K miles... I don't think it was ever replaced, even though the car was supposedly serviced many times by a well known specialist....
Edited by Fenderer on Friday 5th May 13:15
spitfire4v8 said:
Not sure I understand what's wrong with the filter .. the only debris I can see is what you've created sawing it open and sawing through the filter element, unless you can see bits between the pleats which the camera hasn't picked up?
The whole thing is coated in brown sludge, lots of it. 
Fenderer said:
spitfire4v8 said:
Not sure I understand what's wrong with the filter .. the only debris I can see is what you've created sawing it open and sawing through the filter element, unless you can see bits between the pleats which the camera hasn't picked up?
The whole thing is coated in brown sludge, lots of it. What do you think the brown sludge is ?
Paulprior said:
Don’t forget that there is a small hose from the fuel rail to the pressure regulator just behind the plenum
This small hose is redundant if you also omit the short bent steel tube that in a TVR serves no useful purpose. You can than connect the return fuel line direct to the pressure regulator. The fewer connections in the fuel hoses the better!I suspect you've done the job on this by now, but I'm going to replace part if not all of my return line as I've got cracking on the rubber section in the rear wheel arch.
I have had an email chat with Paul from Bertram Hill having read the article, and was digging into doing SS braided rubber (or PTFE) on the return from the pressure regulator to the tank in one length. My supply side looks fine for now (has a relatively new pump and very new filter too), so I'll monitor it but leave that as a future concern.
Paul suggested Cohline (Mercedes OEM):
https://www.merlinmotorsport.co.uk/p/stainless-ste...
I've seen the discussion that challenges using SS braided because you can't see the condition of the hose within, though I'd guess at an 8-10 year lifespan for such a hose, so would relax for a few years unless a leak appears.
I also spotted this hose as a cheaper alternative, but have no perspective on quality.
https://siliconehoseuk.co.uk/collections/rubber-st...
In my case, the passage of time and outdoor living are my main enemies, not mileage. The car will go on a track in my ownership, and spirited driving is comparatively rare, so wear is not a huge thing.
My main question becomes how easy it is to get that final bend onto the tank return pipe if it's SS braided rubber, and if braided PTFE could make that bend at all - any suggestions?
I have had an email chat with Paul from Bertram Hill having read the article, and was digging into doing SS braided rubber (or PTFE) on the return from the pressure regulator to the tank in one length. My supply side looks fine for now (has a relatively new pump and very new filter too), so I'll monitor it but leave that as a future concern.
Paul suggested Cohline (Mercedes OEM):
https://www.merlinmotorsport.co.uk/p/stainless-ste...
I've seen the discussion that challenges using SS braided because you can't see the condition of the hose within, though I'd guess at an 8-10 year lifespan for such a hose, so would relax for a few years unless a leak appears.
I also spotted this hose as a cheaper alternative, but have no perspective on quality.
https://siliconehoseuk.co.uk/collections/rubber-st...
In my case, the passage of time and outdoor living are my main enemies, not mileage. The car will go on a track in my ownership, and spirited driving is comparatively rare, so wear is not a huge thing.
My main question becomes how easy it is to get that final bend onto the tank return pipe if it's SS braided rubber, and if braided PTFE could make that bend at all - any suggestions?
The return is high up the tank angled downwards slightly from memory so I would be fairly confident either would work.
I like the ptfe braided hose but what is the suitability for fuel like?
Also just to add make sure you can use a decent clip method on the ptfe as its a bit more rigid.
I like the ptfe braided hose but what is the suitability for fuel like?
Also just to add make sure you can use a decent clip method on the ptfe as its a bit more rigid.
Edited by Belle427 on Tuesday 23 May 16:17
I took a closer look at the connection to the back of the tank, and even the old (quite cracked) rubber hose is slightly flattened in the curve to make that bend, so I'm not confident the PTFE hose will flex to a radius that tight, nor would SS braided.
From what I can tell, PTFE is the best option for petrol/ethanol resistance, taking up to 50% ethanol. I only use E5, not had the need to fill up with E10 as yet, so I'd be very comfortable using PTFE that's earmarked for fuel.
It also look like with a bit of careful fiddling I could replace that hose without having to take the tank out.
I'm going to siphon the tank to minimise loss, but this would be great if I don't need to undo much more than two clips in a tight space. I'll try it and see if I can achieve it.
My current inclination is to just fit a new section of marine grade rubber fuel hose, and keep a bigger version of this job for a later date when that hose starts to fail in a few years.
Will report back...
From what I can tell, PTFE is the best option for petrol/ethanol resistance, taking up to 50% ethanol. I only use E5, not had the need to fill up with E10 as yet, so I'd be very comfortable using PTFE that's earmarked for fuel.
It also look like with a bit of careful fiddling I could replace that hose without having to take the tank out.
I'm going to siphon the tank to minimise loss, but this would be great if I don't need to undo much more than two clips in a tight space. I'll try it and see if I can achieve it.
My current inclination is to just fit a new section of marine grade rubber fuel hose, and keep a bigger version of this job for a later date when that hose starts to fail in a few years.
Will report back...
It is possible to replace the return hose at the tank. Just undo the tank retaining straps and pull it back a couple of inches. You might have to remove the filler neck hose as well. When I did mine I had replaced the outlet hoses from the tank to the fuel pump. A few weeks before so they were flexible.this might have helped.
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