Fuel Line Tubing

[rickf]

The fuel line going into my mechanical fuel pump looks like it is made of some sort of black plastic. I've read that plastic parts in the fuel lines have been prone to failure, such as the T-fiitting between the carbs. Is this black plastic tubing safe or should it be replaced?

[+2R160]

Rick, it is black plastic tube - I have just removed mine as I am fitting a new alloy fuel tank into my +2. For my new fuel line I am going to use 8mm stainless braided hose which is a direct fit to the new fuel tank, but I have yet to check the connection into the fuel pump, which may require a different fitting.

Bear in mind that the connection from the tank to the mechanical fuel pump is low pressure and so is less critical than the high pressure connection from the fuel pump to the carbs. However, having just removed the plastic line and seen that it runs through the centre of the chassis above the propshaft and the exhaust, I would personally be thinking of replacing it - new fuel tank or not. I would certainly suggest that next time you are under the car, you check that the line is still fitted properly in its clips and is well out of the way of the propshaft/exhaust!

I sourced the new line from GPR (www.gprdirect.com) and it was reasonably priced I thought at ?4.76m.

Regards, David.

[steveww]

The fuel line run from the tank to the pump on my S4 is stainless braided. However the pump is electric and right next to the tank. The run from the pump to the carbs is a solid metal pipe similar to brake line but bigger dia obviously.

[richboyd]

While the original fuel line was plastic, I worry about reformulated gasoline (MTBE, ethanol, methanol, who-knows-what next) having a negative effect on the original-type plastic. If the original line is nylon, it is probably OK - but who knows what it is.

I decided to use 5/16" aluminum tubing for the stretch running from boot/trunk to engine bay. I supported the tubing generously with "P" clips and joined sections with AN-5 fittings. I'm sure this is overkill. I have too much time on my hands. But at least is will be durable: it won't leak and it won't melt.

The plastic "T" fitting between carbs is notorious for its failure rate. Probably the type of plastic it is made from. You may find yourself wanting to use additional plastic fittings elsewhere. There are several types of plastic that will handle modern gasoline mixtures, and many that will not.

I chose to use Kynar brand PVDF (polyvinylidene Fluoride - related to teflon) for all hose fittings (such as the carb "T"). Kynar will take any fuel mixture you throw at it and will last longer that the hose you use it with. Many nylon formulations and HDPE (high density polyethylene) are not bad with gasoline. Stay way from polypropylene (Nalgene) and PVC (polyvinyl chloride).

[rickf]

No leaks or anything yet, but it looks like something I should add to my list of things that need doing. The stainless braid sounds like the easiest to fit. The tee's been replaced with brass, so I should be good there.

[brassringfarm]

When I built my Elan, I bought new tubing from Dave Bean. It goes through holes in the bulkheads near the propshaft which are rounded and clears the propshaft well. The tubing is thick and fairly stiff, but not brittle. Conections are made via a compression AN type fitting at the fuel pump and via a short length of rubber tubing and clamps at the rear. Personally, I had a bad leak with the braided tubing I had that went from the fuel pump to the carbs. It sprayed gas all over everything till I noticed it. The problem was pinhole leaks in the rubber itself. The braiding basically did nothing except look nice. Net - I've been happy with the original plastic tubing the three years it's been in the car.
Paul
65 S2

[archigator]

When I bought my '71 Elan Sprint in 1988, I replaced the gas tank with a Dave Bean stainless steel tank, and was also shocked to find the plastic line running from the tank to the fuel pump. I called Dave Bean, and they suggested that I stay with the plastic line, albeit a newly purchased one. They told me they'd never heard of a problem with it. However, the plastic tee fitting from the fuel pump to the carbs is notorious for melting/leaking... right over the distributor. I replaced the fuel line from the original fuel pump to the carbs with aeroquip hose and fittings. I've never had a leak anywhere.

Gary
'71 Elan Sprint

[dmreeceuk]

I would also add my comment on braided hose. Essentially its a steel braid to stop the rubber hose underneath swelling under high pressure. Much higher than we would see either with a mechinical pump or electric pump in the boot! I also didnt like the idea of the braid which could split and end up piercing the rubber like little needles(prob very unlikely!)

It may look nice and shiny but who sees it down there! I replaced the plastic pipe with conventional rubber petrol hose(from any motor shop). There are two types, ones for fuel injection and the other for standard carbs. The fuel injection pipe has nylon?? threads actually woven into the hose to stop it swelling under perssure. I also checked the temp rating by placing a section ontop of the exhaust as a test. I showed no sign of melting as the plastic would do. I guess its safe for over 100C permenantly as it looks similar rubber to what we use for our water hoses.
Cheers

Dave

S4 1970

[asc]

I have run the same piece of black nylon pipe from tank to pump for years without problem on my S2. As long as its in good condition, well clipped in place it should be ok, after all its on the suction side of the pump, main area of concern is on the pressure side to the carbs. Tony

[niallf]

These people have huge stocks of hose in all sorts of sizes. Quite a good on-line catalogue too.

<a href='http://www.desihose.com' target='_blank'>Designation</a> - Wierd name, I know.

Look under Oil for Petrol Hose, or just do a search for Petrol. I've just bought a whole pile of 8mm I/D 10 Bar petrol hose from them for my Zetec +2 project. They seemed very helpful.

Niall

[elancoupe]

In my case, I have a Fuel Safe fuel cell with AN connections on it. I purchased an electronic pump and filter with AN connections as well, so that my fuel system is braided line from tank to carbs. No leaks and easily serviced, albeit a bit pricey.

Because of the larger OD of the braided line, it was necessary to enlarge the holes in the chassis where the hose passes through. Following this step, I fitted grommets in these holes.

[elansprint71]

I am just going through the chassis/frame replacemnet scenario and have purchased a length of fuel tubing from Spyder; it is some sort of white translucent plastic and they told me that it was resistant to "anything". I am not sure if this includes the detonation nearby of a thermo-nuclear device but I would not be that interested if it failed under these, far from likely, circumstances.
If you are tempted to fit a rigid line from tank to mechanical pump (on engine), bear in mind that there is a good deal of movement between engine and chassis, so a short length of flexi pipe is needed to connect to the pump.
I think one needs to be careful when selecting S/S braided pipes, as already commented, the S/S looks good and is fine for mechanical protection from the outside but the inner pipe needs to be resistant to whatever is flowing through it.

Pete

[richboyd]

Pete,
Agreed, you absolutely need flexible line between chassis and engine. My use of aluminum tubing runs from Facet electric pump in trunk near fuel tank to a pressure regulator (set at 2.5 PSI) in engine bay. The regulator is mounted to the body under the carbs (room exists there with LHD) so it doesn't move with engine. I make the jump to carbs with flexible plastic fuel line. This blue hose is made by Bing (the carb company), is alcohol resistant, and is sold by Aircraft Spruce. Not fancy looking, like the stainless covered stuff, but at only 2.5 PSI it should be fine. I also use the same Bing fuel hose between tank and pump; a short distance in the trunk and on the vacuum side of the pump.

Like you, I ordered a section of plastic fuel line from Spyder, along with a chassis, shocks, springs, etc., etc. Of the seventy or so items that I ordered from Spyder, the only thing they failed to ship was the plastic fuel line. I would have used it if I had it. Instead, I went to the aluminum tubing. I am very happy with all of the stuff I got from Spyder; real first class parts, nothing cheap. Love the chassis.

Rich Boyd

[trw99]

This thread is close to a problem I was asked about. The braided stainless fuel lines from pump to carbs had rotted and needed replacement. Fuel was seeping way too freely from them and we can all imagine the consequences of that.

In answering my questioner, I did some research on fuel lines, which gave some cause for concern. Unleaded petrol and the ethanol now added to it is apparently notorious for rotting rubber fuel lines. These fuels become extra-corrosive when they get old and stale fuel left in an unused car becomes more corrosive.

Braided fuel hose is just rubber inside and is starting to gain some notoriety for collapsing internally. Black bits of rubber appearing inside the fuel pump and fuel smells at rest are early signs of this rotting. In looking to replace these fuel lines we are advised to use pipe to J30R9 standard. Here is some additional info I found:

Hoses in the USA are marked with an SAE code, eg. SAE J30R9, according to its ability to resist modern fuels. Since much of the hose bought in the UK is made (or sold) in the USA then these markings may appear here. There are 4 significant groups of SAE codes:

Unmarked hose - Will probably be for the original leaded petrol formula, without modern additives
J30R6 - 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
J30R7 - This is the standard for the petrol formula of 2 - 3 years ago, for fuel injection. The bore is lined with Nitrile
J30R9/J30R10 - This is the current standard. The bore is lined with Fluoroelastomer/Nitrile. J30R9 has Fluoroelastomer/Nitrile on the inside, while 30R10 has it inside and out, which allows it to be immersed in petrol (eg. in a fuel tank)
There is also a marine grade for use in boats - ISO 7480 A1, that is roughly equivalent to J30R7-and-a-bit, with added fire resistance
The USA seem to use a higher percentage of alcohol in their regular fuel - but we're not far behind in Europe

I am no scientist or fuel expert. However given the flammable nature of our cars I felt this deserved an airing. Does anyone with better knowledge of fuels, rubber etc know any more that would enlighten us?

Tim

[512BB]

When I read your posting Tim, I started off at the top of the thread. I thought, crikey, havent heard of these posters before, then I looked at the date of the original post, 2004.

It seems that a lot of peeps have left Lotus ownership, or at least, no longer comment. Part timers.

Thanks for the heads up on the tubing side of things. Stay safe out there Elan owners, check your tubes and ALWAYS carry a fire extinguisher that will do the job should the worst happen.

Leslie