Fuel pump / Fuel lines

[audiomick]

Hallo.

I had a look at the fuel lines on my V11 Le Mans today, and noticed it was sweating a bit of fuel where the fuel line comes off the attachment under the tank.

It looks like mine is this version, i.e. fuel pump in the tank:

https://wendelmotorraeder.de/benzinleitungen-v11-02-le-mansskura-ex-30_3006_300602_30060203_3006020310_300602031016.html

The link leads to a page of the parts lists at Wendel Motorcycles ( Wendel Motorräder ) in Berlin.

Under the tank, instead of part #5 on the drawing, that apparently looks like this:

 

There are hose clamps such as those that part #7 apparently are:

so it would seem that someone has already been messing around with it at some point.

I had already tightened up the outer clamp of the two, i,e. the one closer to the riders knee, which was loose enough to be able to turn it on the fuel line with very little effort when I took delivery of the bike. Today I noticed that it wasn't actually clamping the fuel line. I don't know for sure if I had tightened it onto the fuel line as intended, or if I missed the fuel line the first time round. The fuel line isn't pushed all the way up the "nipple" it is on, and I couldn't move it any further up today. Doesn't surprise me really, I was outside, and it was only about 3°C, so the fuel line was hard as rocks and not inclined to be moved. As far as I could tell, there was at least the width of the clamp of the nipple inside the fuel line, and maybe I have got it solved for now. I'll definitely be having another look at it though.

Anyway, I have a couple of questions that I hope someone here can answer:

I assume, since the fuel pump is in the tank, that the blow-off to regulate the pressure in the fuel lines is also in the tank. Going by the drawing, the two connectors are one each for the two throttle bodies. Is that correct?

Edit: strike that one. I've had a look at a workshop manual. In there, it says that the "outer" line is the feed to the injectors, and the "inner" one is the return.

How much pressure is in the fuel lines? Given that the fuel lines are held on by clamps, it can't be that much, can it?

What is the considered opinion: should tightening the clamp (assuming that it is sitting correctly and clamping enough of the fuel line...) be sufficient to solve the sweating problem, or do I urgently need to have a closer look?

I'm assuming, for the moment, that the hose is really fuel line, and not just some rubber hose that might be starting to disintegrate due to the effects of the fuel.

 

One further question: from what I have read, the connectors that come off the bottom of the fuel pump, i.e. out the bottom of the tank, are a bit fragile, and need to be handled with care. With regard to that, I wasn't too keen on trying too hard to push the fuel line further up the nipple. Is that correct, or am I being too cautious there?

 

Thanks in advance

Mick

[docc]

The fuel pressure is 3 bar (40-45 psi), IIRC.

How about using high pressure "fuel injection" style clamps?

Otherwise, perhaps your hoses have hardened to the point they will not seal well . . .

[docc]

7 minutes ago, KINDOY2 said:

I ONLY use these.. 

These require a special tool to crimp? Are they re-usable?

https://www.oetiker.com/en-us/

[activpop]

Yes,  they require a special tool, maybe $50. I use these connectors a lot on pex piping, but think they are overkill for low pressure fuel lines. I might use them if they were easy to take off, but they are not. They have to be cut off, and too much force might be put on what they are attached to. 

[activpop]

I've used pliers many times to take them off, but not a screwdriver. I'll try that next time,  but I think it still exerts some force on the stem it is connected too, doesn't it? I know the pliers do. I've been using these for thirty years, but never for fuel. I think my Ducati has them inside the tank on the pump lines which I have to replace, so I'll try it there. What are you calling the tab end? 

[MartyNZ]

If you have sweating and stiffness in a V11 hose, I believe that you should replace it. If original, it is 20 years old now.

Make sure that you get the right specification of hose. The correct material for sub 50psi external pressure hose will not last if submerged in fuel. The correct material for hose immersion in a tank will not last outside when exposed to sun and heat. Low pressure hose for carburetors is not suitable for injection systems.

A good summary is given here, both for hose and hose clamps.

https://www.onallcylinders.com/2021/10/24/buyers-guide-how-to-pick-the-best-flexible-fuel-hose-for-your-vehicle/

[gstallons]

This is an important and good read . If you are going to use the crimp type hose clamps , practice using the clamp/tool on a practice hose to get good at this style clamp system. You say your bike has the "in tank" fuel system ? Be careful working around these fittings. You break this stuff and you are going to be ANGRY !

[al_roethlisberger]

This is a great thread. 

 

Once validated, it would be helpful for future reference for someone to post the correct hose type and size for the external lines on a 2003+ (in-tank fuel pump) model.

 

Then it will be tracked here, and maybe in the FAQ section later.

 

The thread below has a little additional information I gathered about the 2003+ (in-tank fuel pump) tanks:

 

 

 

 

 

[activpop]

5 hours ago, gstallons said:

This is an important and good read . If you are going to use the crimp type hose clamps , practice using the clamp/tool on a practice hose to get good at this style clamp system. You say your bike has the "in tank" fuel system ? Be careful working around these fittings. You break this stuff and you are going to be ANGRY !

Clamping is pretty easy, one controlled squeeze of the tool and its done.  You can't over or under tighten.  It's the removal where there is a bit of risk. They don't come off so easy. Stainless steel is a metal that does not take to cutting easily. My method of removal has always been using a pair of diagonal cutters gripping the base of the crimp and twisting until it snaps...there is some force involved and backing up what it is attached to is important. I tried what I think Kindoy2 suggested, I couldn't get it to snap off.  I must be missing something.

[audiomick]

Thanks for all the good answers so far.