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Fuel Hose Warning


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#1 dsgoody

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Posted 19 July 2020 - 11:54 AM

I had an issue a few weeks ago where fuel was leaking from the inlet of my carb and down onto the exhaust manifold. Had I have not caught the issue it could have caused a fire. It’s highlighted the importance of correct size fuel hose; so I’m going to leave this information here to hopefully help some people out. I'd advise anybody to go out and check their fuel hose and make sure it is secure and fluid tight.
 
I’ve taken a lot of influence from here; http://www.volksbolt...aq/fuelhose.htm so please credit these guys for a very helpful resource.
 
Correct I/D Sizing
Most Mini suppliers will sell you 1/4” (6.35mm) internal diameter (I/D) fuel hose. This is perfectly suitable for beaded 1/4” inlets however on measuring up the inlets on my original HF38 carb, original fuel pump and current HIF44 carb what did I find;
They are all 6mm! Ideally, a rubber fuel hose should be stretched slightly over the pipe to form a fluid tight seal; so a slightly smaller 5.5/5.6mm I/D pipe should be used to ensure a fluid tight seal. On a pipe that has beaded ends a 6mm I/D pipe could be used safely as it’s stretched over the bead (in my opinion), but a 5.5/5.6mm hose would offer a better seal.
 
My HIF44 carb not having a beaded end; I should have been using a 5.5mm I/D hose and not the supplied 1/4" (6.35mm) hose. After a few years of wear it stopped gripping the pipe and started leaking fuel; so much so that even with the supplied clamp fully tightened I could just pull it off the carb with no force at all. I've replaced it with this smaller (and Ethanol proof) hose;
https://imgur.com/aqRkMQm (old on left; new on right)
 
Correct Hose Clip Sizing
Another issue I encountered was incorrect clip sizing;
This 1/4” hose has an outside diameter (O/D) of 12mm; but the supplied clips were 13 to 15mm. A clip of 11 to 13mm should have been used; allowing adequate and mostly even clamping force onto the pipe.
 
For reference I replaced all my fuel hoses with this;
Cohline 2240 5.5mm I/D with 10 to 12mm clips
Cohline 2240 7.3mm I/D with 12 to 14mm clips (for my 8mm tank feed on HIF38 cars)
This was my personal choice for peace of mind; but there are perfectly suitable cheaper options out there.

Edited by dsgoody, 19 July 2020 - 03:42 PM.


#2 DB1380

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Posted 19 July 2020 - 12:58 PM

Yes to this above.

Im not a great fan of Braided Hoses either....hard to see splits or wear.

 

Ive seen one or two Aircooled VDubs go up in smoke due to crap fitting fuel lines. Them Campers do burn well !!



#3 pltudinous

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Posted 19 July 2020 - 02:03 PM

I've just discovered that my overflow pipe aims at the exhaust, so I'm achieving this a different way, but cheap fuel lines are definitely scary! Couldn't imagine losing the car to something as simple as cheap fuel line

#4 mab01uk

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Posted 19 July 2020 - 02:42 PM

Minispares - Orange band denotes - Made to specification to cope with modern ethanol based petrol:-

http://www.minispare...assic/PPK7.aspx

 

GENUINE SU HS STAYUP FLOAT KIT

The new adjustable height StayUp® Float is resistant to modern ethanol Based Fuels and has a military spec closed cell construction making it puncture proof.

http://www.minispare...00.aspx|Back to


Edited by mab01uk, 19 July 2020 - 02:46 PM.


#5 I hate Brian

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Posted 19 July 2020 - 03:04 PM

Very helpful thanks for the info  :highfive:



#6 dsgoody

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Posted 19 July 2020 - 03:40 PM

I've just discovered that my overflow pipe aims at the exhaust, so I'm achieving this a different way, but cheap fuel lines are definitely scary! Couldn't imagine losing the car to something as simple as cheap fuel line

Nor could I; glad I caught it before it could have become a problem. I have a pipe on mine from the overflow, that joins to a steel line and takes the float vent away over the top of the clutch and down the front of the engine.

 

Minispares - Orange band denotes - Made to specification to cope with modern ethanol based petrol:-

http://www.minispare...assic/PPK7.aspx

While I agree replacing components with Ethanol proof variants is a good idea; the issue in my case was the use of 1/4" fuel line and it not being appropriate for every Mini (certaintly wasn't for mine).



#7 I hate Brian

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Posted 19 July 2020 - 04:12 PM

So what fuel lin did you have originally ? I'm using an existing SPI pipe to feed my hif 44






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