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DerekJ

Rubber fuel pipe

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Hi All,

Just taking my fuel system out for the winter and found the rubber pipe badly cracked (photo in a while). Fortunately it was the return line from the swirl pot, after the restriction, so was at very low pressure. Even so, not a nice thing to find.

pipe.png

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As Blatters would have said in days gone by...do a search. There's a mountain of stuff on rubber hoses and modern fuels with increasing bioethanol content. I'll find one and link to it....

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I posted this on the Locost forum a couple of weeks ago. Should have posted it on here as well I guess. Better late than never.

Check your fuel pipes

A timely reminder for all you happy people out there not to forget your fuel pipes on your pride and joy. Might be a long post but bear with me.

Built my car in 1992, x-flow, carbs etc, just used rigid plastic fuel pipe with a small piece of reinforced petrol pipe at either end to connect to carbs and pump etc. It ran like that until 2001 when I fitted a Zetec on carbs and did not touch the pipes or anything and I never had a problem.

During the winter of 2004/2005 I fitted injection to the car using an MBE ECU, Jenveys etc. Obviously I needed to put high pressure pipes in and a return and after much investigation and discussion decided on Moquip TFE hose from Think Automotive. Its main selling point was the fittings which you can fit without special tools plus if you get it wrong you can re-use them two or three times. All went well but I quickly discovered it was not the easiest stuff to work with, the hose is extremely high quality but the braid is lethal when you cut it and is can be difficult to work with in tight spaces i.e. tank to LP pump and LP to swirl pot swirl. Because of this I decided to use a 8mm braided steel hose from another well known retailer of kit car parts that they guaranteed was compatible with unleaded and was easy to work with. The pipe from the bottom of the swirl pot to the main filter and from the main filter to the HP pump was always intended to be 12mm rubber and the bled from the top of the swirl pot to the tank 6mm rubber.

All went well and I had no problems but in July 2009, just over 4 years after first using the car with injection I got a terrible smell of petrol when I went out one Sunday. When I stopped I spotted a drip from the swirl pot and immediately drove the 3 miles home. By then the smell was really bad and the gauge was dropping like a stone. To get to bolts and the pipework I had to remove the interior trim and I found to my horror the carpet under my seat was soaked in petrol, I had been sat in a bomb. On inspection all the Mocal TFE stuff was fine but the cheaper braided pipes simply disintegrated when I tried to remove them as did the 12mm hose. However, the 6mm bleed pipe was fine but it flows very little fuel since there is a 1mm restrictor in the pipe. I was not happy to say the least.

After much phoning round I was convinced to use 8mm and 12mm cotton braided fuel hose by another well known supplier of fuel system components, I was guaranteed it was up to the job.

Just over 3 years on from that experience I decided to check the hoses and guess what, virtually the same again. The 12mm and 8mm have started to crack as has the 6mm return but that has taken 8 years, looking at them they would fail some time next year if they remained on the car.

So the 8mm is being changed to -6 Mocal TFE which I should have done originally and the 6mm will be replaced with -3 Mocal TFE hose. The 12mm is a bit of a problem since no one appears to do 12mm R9 but I am prepared to live with a lower spec in the area (R7?) because its easy to change and has to be removed to change the fuel filter anyway.

The problem with the R9 stuff appears to be its only available in imperial sizes and all my unions are metric plus there are loads of stories about cheap Chinese stuff simply being marked as R9, got to think about that one since the air bleed union on the swirl pot is welded on.

So please check your fuel pipes

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