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Author: Subject: Fuel pipe research (long!) - for discussion!
David Jenkins

posted on 4/4/11 at 03:06 PM Reply With Quote
Fuel pipe research (long!) - for discussion!

You may recall that I had a rant about rotting flexible fuel pipe a while ago (LINKY).

In the end I did a lot of internet research, and came up with the following observations:

Background

* Since getting my car on the road 7 or 8 years ago I have had to replace rotted flexible fuel hoses 3 times. Each time the hose has cracked and was dripping fuel everywhere.
* I have always used decent quality hose (Gates, or similar).
* It seemed to happen randomly but especially after a long spell in the garage, whether due to bad weather or whatever. (significant point #1)
* Some other people had similar problems.
* More people were using similar hose and having no problems (significant point #2)

Results of research

* Petrol has changed significantly over past few years - it now contains more alcohol-based substances, which are very corrosive to normal rubber.
* Hoses in the USA are marked with an SAE code, e.g. SAE J30R9, according to its ability to resist modern fuels. As 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 petrol formula, without modern additives (but see later comments).
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.
30R7 - This is the standard for the petrol formula of 2 or 3 years ago, for fuel injection. The bore is lined with Nitrile.
30R9 / 30R10 - This is the current standard. The bore is lined with Fluoroelastomer/Nitrile. 30R9 has Fluoroelastomer/Nitrile on the inside, while 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.
* One of the causes of fuel pipe failure described in the USA literature is stale modern fuel, not so much the fuel itself. These fuels become extra-corrosive when they get old.
* The USA seem to use a higher percentage of alcohol in their regular fuel - but we're not far behind in Europe.

What got me angry...

* Gates in the USA only make and sell fuel pipe of grade 30R9 or better (they even have brand-new super-grades). Gates in the UK distribute unmarked hose to motor factors that, if you are lucky, is only 30R6. Why don't we get the same? Are they dumping their surplus stock on the UK?
* The Gates sales rep for the UK and Europe didn't know that the USA grades were far higher than his offerings - he didn't even know the trade names for the USA products (shown in every USA Gates catalogue).
* 30R9 is freely available on the USA ebay, at sensible prices, made by big-name manufacturers such as Gates and Goodyear. It is never (or maybe rarely) available on the UK ebay. Only the excessive postage stopped me from buying it there.
* One on-line supplier (Think Auto) advertised that their hose is 30R9, but when it turned up it was unmarked. I recognised that it was stuff that I'd used previously and told them so. To their credit they apologised, refunded my money AND paid for the return postage.
* There is a general ignorance about this whole issue - when I asked for a specific grade of hose many suppliers didn't comprehend, while others were almost abusive ("Our stuff is good enough...!).
* The one who did supply the correct hose, Hose World, advertised it as 30R10 on their website, the bloke on the phone didn't think it was any special grade when I asked, and when it turned up it was 30R9, which is what I was after in the first place!
* If you search on any USA car forum about fuel pipe you will see that most people are fully aware of this issue, and the need to use modern hose. There seems to be a general ignorance in the UK.

Last thoughts and recommendations

It was almost certainly stale fuel that rotted my fuel pipe(s).

1. Don't buy general-purpose hose from a motor factor, unless it has at least 30R9 printed on it. Even stuff off the Gates stand isn't good enough.
2. If you are getting it via the internet or mail order, don't be fobbed off by excuses. Only the proper stuff is safe for long-term use.
3. If you are going to leave your car unused for a month or so, consider draining the petrol, especially if you are unsure of your fuel pipe grade.
4. If you really can't get 30R9, consider getting ISO 7480 - this is easily available from marine suppliers in the UK (but see point 3). All proper fuel pipe in this grade has to be marked, to meet regulations.

Additional thought

Re-reading some of the websites I found during this research reminded me of an important indication of fuel pipe decay - smell.

If you go into your garage and there is a stink of petrol, but you can't find a leak, then it is very likely that vapour is permeating through the fuel hose. If this is the case then it is a fair bet that the hose will fail sometime in the near future... maybe not immediately, but sometime.

[Edited on 5/4/11 by David Jenkins]





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BenB

posted on 4/4/11 at 03:13 PM Reply With Quote
Very interesting research! Kind of makes sense about the old fuel I suppose. The alcohol probably oxidises into all kinds of acidic nastiness. I could vouch on Sunday morning that an excess of old alcohol based fuels is not a good thing
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chrsgrain

posted on 4/4/11 at 03:40 PM Reply With Quote
Thanks for that - its a good summary. There is a lot of concern in the classic car world about this at the moment, as they are the sort of cars that sit around for a while, and often have older fuel systems and older piping. There is even concern that some old copper fuel pipe may not be sufficiently resistant - that sounds a bit of an overreaction to me, but it certainly will affect diaphragms in fuel pumps and carbs....

Oh yeah, and it will knacker brass fittings as well...

All in all, a pain in the arse.

Chris

[Edited on 4/4/11 by chrsgrain]





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rb968

posted on 4/4/11 at 03:44 PM Reply With Quote
Interesting. Many thanks.

I have a long run of rubber hose (Gates but not sure on its markings) which I know I need to replace with hard pipe post IVA so will be having a good look at it this week.

I can imagine my local motor factors reaction if I ask for a certain grade......miserable sods at the best of times.

Rich

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DarrenW

posted on 4/4/11 at 03:52 PM Reply With Quote
Kunifer plus shortest poss lengths of rubber sound sensible - ideally in easy to access / inspect / replace places.

What do OE's use?






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MikeRJ

posted on 4/4/11 at 03:54 PM Reply With Quote
Excellent post, this really needs to be stickied.


quote:
Originally posted by DarrenW
What do OE's use?


It seems to be mostly some kind of semi-rigid plastic these days.

[Edited on 4/4/11 by MikeRJ]

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Mr Whippy

posted on 4/4/11 at 03:58 PM Reply With Quote
quote:
Originally posted by BenB
I could vouch on Sunday morning that an excess of old alcohol based fuels is not a good thing


probably best pouring that sh%t in the tank






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David Jenkins

posted on 4/4/11 at 04:13 PM Reply With Quote
quote:
Originally posted by DarrenW
Kunifer plus shortest poss lengths of rubber sound sensible - ideally in easy to access / inspect / replace places.



That's the setup I've got - except I've got 8mm copper pipe, which I've found to be too soft, particularly when trying to push FI hose onto it! I'll be upgrading to Kunifer next time I've got the engine & gearbox out.

quote:
Originally posted by DarrenW
What do OE's use?


As said elsewhere - they use some form of hard plastic pipe. I tried to get info on that, but it's not generally available. Many OEMs seem to use custom connectors as well.

What annoys me a bit is that there is flexible pipe on my ex-bike fuel pump - it's thin, and VERY flexible, and would be ideal as it shows absolutely no sign of rotting - it's as good now as it was when I installed the pump 2 years ago. I asked in a few bike shops but it's not generally available.

The local bike shop did have some fuel pipe that they use, and it looked quite different to regular car hose - but it was unmarked and I didn't want to risk it. Shame, as I don't need the stiff and unwieldy FI hose as I'm using carbs.





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James

posted on 4/4/11 at 05:17 PM Reply With Quote
Thankyou for the excellent and informative post David!

Bit worried about my Locost now which has been sitting for 3 years!
The long run is that expensive plastic coated ali stuff sold by Tifosi but the rest is probably Gates at the rear end and metal braided rubber at the front sold by Tifosi... so could be anything! lol

And my Mk2 Golf'a been sitting for 1-2yrs!

Cheers,
James





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ReMan

posted on 4/4/11 at 05:30 PM Reply With Quote
Great info
What I can't understand is why the flexible rubber hose fitted to production cars and bikes evn at nearly 20 years old does not have these problems?





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r1_pete

posted on 4/4/11 at 05:36 PM Reply With Quote
10 mm nylon fuel line 7.5 metre length on eBay (end time 30-Apr-11 10:44:22 BST) is the stuff many OEMs use, I did ask about modern fuels, here's the response:

Hi Pete,
Thanks for asking.

Our supplier has been supplying fuel and hose products for 30 years, and states that this problem does not apply to his nylon fuel line, there can be problems with rubber hoses with modern fuel, but we don;t sell rubber hoses. SUpplier confirms there is no degradation even with 100% ethanol fuel in the nylon hose we supply.

Hope this is OK for you and look forward to receiviing your order. We can supply in 100 ft lengths as well if you are interested.
Best Regards
James

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David Jenkins

posted on 4/4/11 at 05:46 PM Reply With Quote
That looks like interesting stuff. I wonder what the internal diameter is - any idea?

OOPS! Just spotted "8mm internal" in the advert!

[Edited on 4/4/11 by David Jenkins]





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Mr Whippy

posted on 4/4/11 at 05:54 PM Reply With Quote
quote:
Originally posted by ReMan
Great info
What I can't understand is why the flexible rubber hose fitted to production cars and bikes evn at nearly 20 years old does not have these problems?


hmm and I use fuel hoses that are from the 70's and are still fine






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David Jenkins

posted on 4/4/11 at 06:00 PM Reply With Quote
That's what puzzled me originally - different people get different results. I think that there are several factors involved: for me, I think the biggest is that fuel sits in the rubber pipes next to the tank for long periods, and gets stale. Those pipes rot, but the ones up by the carbs don't because the fuel drains back from there when the engine isn't running.

As for OEMs - most cars I've seen have hard piping from the tank right up to the engine compartment, so maybe the rubber tubes rarely sit filled with fuel for long periods?

This is why I put "for discussion" in the title of this thread!





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blakep82

posted on 4/4/11 at 06:03 PM Reply With Quote
but short 6" sections of rubber hose are surely 'as likely' to rot as a rubber fuel line from tank to carb?
in the next few weeks i'm doing mine with nylon pipe anyway. as much as i can...





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ReMan

posted on 4/4/11 at 07:17 PM Reply With Quote
quote:
Originally posted by Mr Whippy
quote:
Originally posted by ReMan
Great info
What I can't understand is why the flexible rubber hose fitted to production cars and bikes evn at nearly 20 years old does not have these problems?


hmm and I use fuel hoses that are from the 70's and are still fine

Agreed. I tried not to exzggeraty by only referencing vehicles I have that are currently OTR, not also from my experiece of older ones too





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David Jenkins

posted on 4/4/11 at 07:51 PM Reply With Quote
I haven't come to this conclusion all by myself... here are a few links on this subject (I can't find my original collection found while researching).

VolksBolts
ClubCobra

There was also a video produced by Gates, but I can't find a link to that any more...

And this one - but there is NO EVIDENCE that this was caused by fuel-affected fuel pipe - makes you think though...

MX5

[Edited on 4/4/11 by David Jenkins]





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David Jenkins

posted on 5/4/11 at 07:54 AM Reply With Quote
I have added an "additional thought" to the original post - I had forgotten to list a very important clue that can indicate whether your fuel hose is at risk - smell.

If your car pongs of petrol every time you go into the garage, but there's no sign of a leak, then it's probably due to vapour permeating through the hose. This permeating vapour is what destroys the outer casing of the hose over time.





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wicket

posted on 6/4/11 at 06:57 PM Reply With Quote
Since this problem was first posted I have kept a regular check on my hoses. I have checked them again today and they all look fine, no cracks, no leaks and no smell. They have been in use since around 2004/5, so 6 or 7 years, so I thought it worth posting some details of the hose here.

It came with the new carburettor I bought from Southern Carburettors in April 2004 and he markings on the hose are:

Webcon UK BE 4012 WP Leaded/Unleaded 7,4 3Q01

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RazMan

posted on 6/4/11 at 07:47 PM Reply With Quote
I've got the Nitrile lined stuff sold by my local hydraulic hose supplier and apart from an overtightened jubilee clip which split one hose (since changed to spring clips) all has been fine for 5 years. I'm not sure if it's relevant but I have always used 97RON fuel - maybe it is less aggressive to hoses?





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David Jenkins

posted on 6/4/11 at 08:58 PM Reply With Quote
Perhaps my next bit of research should be to investigate why people get random results with their fuel hose!

Seriously though... there are significant numbers of people who have experienced rotting hose, and a large group of others who have no problems.

Maybe there are mechanical factors (hose clamps, as in RazMan's post) as well as chemical ones?





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blakep82

posted on 6/4/11 at 09:08 PM Reply With Quote
i had a BMW 318 (E30) and kept splitting fuel hoses, in a matter of days
think it was conneced to the redex i was using. when i stopped that it was fine





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wicket

posted on 6/4/11 at 09:18 PM Reply With Quote
My hose clips are like these

http://www.jetpress.com/Products.aspx/17210/HoseClamps/HoseClipsRatchetType/

again supplied with the carburettor.

PS For some reason I am not able to add pictures to posts.

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quadra

posted on 27/4/11 at 01:26 PM Reply With Quote
quote:
Originally posted by r1_pete
10 mm nylon fuel line 7.5 metre length on eBay (end time 30-Apr-11 10:44:22 BST) is the stuff many OEMs use.



This stuff sounds ideal, but how do you terminate the tubing. Do you think it would slip over a barbed fitting like a rubber pipe (possibly after being heated in warm water) and then be secure with a hose clamp around it?

[Edited on 27/4/11 by quadra]

[Edited on 27/4/11 by quadra]

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quadra

posted on 27/4/11 at 01:53 PM Reply With Quote
Ok done a bit more research on the nylon pipe, and this site came up from a thread last year, might be useful to someone.

http://www.tinleytech.co.uk/acatalog/Poly_Pipe__Clips_and_Fittings.html





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