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MG MGB Technical - Fuel hose failure

I was giving my MGB its annual service and pre-MOT check when I noticed some cracks in the rubber fuel hoses on the fuel filter and carbs (see pics). After removing them I cut one open and found that the outer layer of rubber was cracked/split all the way through; the inner part of the hose (that comes into contact with the fuel) seemed ok. I have another length of the same hose stored in the garage as a spare and this doesn’t seem to have deteriorated. The hoses were all purchased and fitted in 2012. They are marked SAEJ30R9 Fuel Injection and were supplied by AFS, who are selling the hose on eBay -
I emailed AFS about this 10 days ago but still await their reply.

Brian Shaw


Brian Shaw

And another one

Brian Shaw

and the fuel line on our 1800 was the same (and leaking}
Roger Walker

Whilst rebuilding the fuel pump last year I took the opportunity of getting rid of the various bling braided hoses. This started an interesting trip about fuel hose.

There is a lot "out there" that either the distributor doesn't know or care what SAE and other numbers he puts on. Many just lump standards for the UK, Europe et al as a long list!

Gates Barricade was reckoned to be the best-until Peter Ugle found that the inner "lining" was detached when pushing on to the barbs, resulting in fuel blockage.

I also have SAE J30R9 bought from an outlet in Hertfordshire. I can't find the details but if you get stuck I will have another look!

FWIW I do not think that ethanol is a threat at present. I was unable to find any conclusive proof that ethanol was the cause of an MGB fuel problem (both here and US). Plenty of supposition but nothing conclusive. (Now watch this space!)

My conclusion was that the inner "lining?" was the anti ethanol bit and the rest suffers from the same poor quality we now get in all things "rubber".

I used loose banjos on the pump and regular clips elsewhere. So far all is well. If I were you I would look either at Modern Main dealer /suppliers or even people who do hydraulic hoses. ie anywhere where a failure is likely to cause sufficient aggro to the supplier so he sells good stuff.
Michael Beswick

Michael - "My conclusion was that the inner "lining?" was the anti ethanol bit and the rest suffers from the same poor quality we now get in all things "rubber"."

That's what I thought was the most likely. When I fitted this stuff 3 years ago it was to replace hose which had only lasted two years which had hardened and started to split (the smell of petrol fumes while driving alerted me to investigate). I can't remember what type or make of hose that was, but most likely not suitable for ethanol. The car was built in 1980 and the original BL hoses were still in good nick when I replaced them in 2008.

Brian Shaw

Hi Brian
I replaced my "Bling" braided hose's about 4 yrs ago after reading about VW camper vans catching fire when split hose's sprayed fuel on engines.
I'm sure it was Chris at Octagon Services who recommended CODON Hose's, mine have printed on them....CODON SAE J 30 R9 FKM-NBR-CPE FUEL HOSE 5.6mm
have just checked they look as new internally & externally after about 10K miles.
W M Griffiths

MGOC and Moss are both selling Codan R9. I've recently bought a length to replace them on the V8, rather than use the pukka braided items as you can't see the condition of those rubber with those.

It will be interesting to see how the new stuff fares, the ones on the pump are original and 40 years old! I've only ever used 95 octane supermarket fuel in it, and done almost 100k over 20 years, so any problems with modern hose are nothing to do with ethanol or unleaded, just crap rubber.

The problem with VW camper vans is primarily the heat from an underpowered i.e. used hard air-cooled rear engine in a hot climate.
Paul Hunt

Correction, MGOC and Moss are selling R6 which is the correct stuff for low-pressure carb systems. R9 is for injection systems and the much higher pressure. If it's good enough for high pressure you may say, it will be good for low pressure. However I wouldn't buy it from eBay, and I would rather see the spec printed on the hose. The other problem is metric hose on ribbed Imperial spigots damaging the inner layer as Peter Ugle found. The only source of claimed Imperial R9 I found was Holden, but at about ten times the price.
Paul Hunt

Paul, couldn't find Codan on the Moss website but they are offering Gates Barricade ethanol-proof
Gates spec for this is SAE J30R-14T1 (useful info on SAE specs at
Brian Shaw

That Moss link will just bring up a full list of fuel stuff. In the search box, type in "fuel hose" (including quotation marks) should bring up the Gates page.
Brian Shaw

Brian & Paul,
I bought mine direct, google Codan R9 Fuel hose, £28. 50p for 1.5M inc. 10 clips Free p&p thats double the amount required, sell half to a mate or keep for spares!!!
Buy cheap buy twice.Regards
W M Griffiths

Brian- Gates Barricade is the one Peter Ugle found dumped bits of the lining in the carb
Michael Beswick

Brian FWIW
Michael Beswick

So, things change all the time. If the Gates hose slides onto the spigots easily then you should be OK. Peter had to force his on which ripped the thin inner lining.

I do find it strange that the Gates five-layer is cheaper than their Cohline (not Codan) two layer!
Paul Hunt

Coincidentally, I started the B this morning and noticed a smell of fuel.

I initially thought one of the float valves may have stuck, as it hasn't run for about four weeks.

I discovered that the hose from the fuel filter outlet had failed. It is possibly the original!

The fuel seemed to be coming out somewhere in the region of the green arrow in the photo.

I found some fuel hose in the garage which was dated 2002. It didn't seem to have deteriorated at all.

Dave O'Neill 2

"I found some fuel hose in the garage which was dated 2002. It didn't seem to have deteriorated at all."

Can't say I'm surprised, keep an eye on it once exposed to heat and fuel.
Paul Hunt

To be honest, I was surprised. In the past, I've had unused heater hose which was cracked, just like Brian's first photo.
Dave O'Neill 2

Changed the V8 pump hoses (RB so two) this morning, swapping the cars over so I could put on the full-length ramps at the back of the tandem garage as even not raised that gives good access under the car.

All quite straight-forward despite having to cut the 'screw and nut' hose clamps off in-situ. I removed the pump complete with hoses as it's only a five-minute job and saves breaking the banjo seals. The almost certainly original 40 year-old hoses were perfect inside and out with the exception of the external braiding which was crumbling away. Just one-piece rubber, no reinforcing layer. I also cut a couple of inches off the filter to carb hose I replaced about 20 years ago. That was also perfect inside but the external edge had a number of radial cracks, that didn't extend under where it had been clamped. Even slitting them lengthwise and flattening them out shows no trace of cracking, as in the attached. 40 year-old hose on the left, with the right-hand end having been over the pipe, the rest in contact with the fuel. 20 year-old on the right, right-hand half with the cracking had been on the carb port. This car has always run on supermarket 95, on its third time round the clock, 100k in my ownership. Confirmation that problems with hoses today are all down to crap rubber, not the fuel, and also that hose probably lasts better when being used than not.

Replaced with cut lengths of plain rubber rather than purpose-made braided with banjos, so I can keep an eye on them.

Just one problem, when testing I turned on the ignition and the pump chattered ... and chattered ... and chattered. Hoses on the right ports, pump the right way up, then eventually I realised what it was.

Any guesses?

Paul Hunt

No fuel in the tank? Sounds like something that I would do. RAY
rjm RAY

Because I'd run the engine just long enough to swap the cars round, the carb float chambers were still full when I came to test it, hence the float vales were shut, and the pump couldn't drive the air out of the system in order to suck up fuel from the tank. When I took the delivery pipe off the carb, directed it into a container and switched on, the rapid chattering almost immediately changed to the steady chunka-chunka as it pumped fuel through. Had me scratching my head for a while :o)
Paul Hunt

This thread was discussed between 16/09/2015 and 25/09/2015

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