Third pipe line location old m600

[Jerryd]

Anyone know qhwew the 2rb runs to in this device. Its the small vacuum pump that fits after the fuel filter. I have the intake correct and out pipe but dont know the smaller pipe. There is nothing there at the moment due to me just putting all back together. haw long id the tube?
I do no recall ever taking it off when I stripped it down.
http://www.ukmonster.co.uk/monster/showthread.php?t=58838&page=8

[slob]

https://i.postimg.cc/0ySYdFsb/Photo-Note-333630554416-6270.jpg

pipe #9 ?
it's the vacuum hose that activates the pump based on intake pressure drop.
should attach to an inlet manifold.

pipe #7 does the same thing for the fuel tap

[Jerryd]

Btw forget the green arrow. Number 4 in the diagram believe ducati call it a pepcock but it is some type of fuel pump

[slob]

‘petcock’ is a vintage word for valve, still used as ‘fuel tap’ in America

[Darren69]

It's a vacuum operated fuel tap. 16 is the fuel pump. There's more plumbing on those old carbie bikes than on the injection ones!

[Flip]

Item 4 (vacuum fuel tap) is fed from the fuel tank via the fuel filter, it is operated as the engine turns over by vacuum pipe 7 and flows fuel via the other pipe (designation out of capture) to the vacuum fuel pump which in turn is operated by pipe 9 and then fuel is fed to the carburettors by pipe 13.

Both vacuum operated assemblies are horrendously effected by the Ethanol in a lot of our pump fuel so it is essential that all vacuum pipes are intact and that both the vacuum tap (which isn’t rebuildable-about £30 from Ducati) and the vacuum pump (which is rebuildable with a kit from Allens Performance) both operate properly otherwise fuel supply can seriously be affected often manifesting itself as a vapour lock in hot weather/heavy traffic/slow riding conditions causing the motor to die.

All bar one of the pipes are still available new from Ducati (remember UKMOC members get 10% discount from Moto Rapido) and most are preformed although I know a couple of people here have replaced theirs with generic fuel pipe of the correct I.D without any reported issues.

[Jerryd]

Thanks for responce. I did a lot of reading and get it now. Very clever desgn you just habe to make sure the small line goes in to the right cylinder down pipe.

[slob]

I don’t think it matters which manifold each pipe is on, both manifolds have roughly (hopefully exactly) the same pressure drop with the engine turning. One operates the tap, the other the pump. Ultimately the length and fit of the stock hoses will tell you which is which.

[Jerryd]

Is ir worth upgrding the fuel pump . If so can I use an off the shelf pump rather then stock Ducati?

[slob]

In a word no, as long as it's working ok/in good condition (see Flip's post #6 above) it's a very low capacity pump, it doesn't take much pressure to feed the carbs, it's nothing like a modern fuel injection pump.

[Flip]

As long as the vacuum tap is working as it should it might still be worth fitting a re-build kit to the pump if it’s never been changed- I did both on mine as I had vapour lock problems and didn’t want to revisit it to change something for the sake of a few quid.

Might be worth getting a JIS screwdriver if the vacuum pump’s not been apart for a while.

https://www.allensperformance.co.uk/shop/

[Jerryd]

I am having problems with the main one. Its intermitant. I have taken it apart and all seems good. No splits. If I use a gravity feed in to the carbs the bike runs okay,
Could it be I am running the bike with the fuel tank up. Would this make a difference?
My logic tells me it should suck the fuel through regardless,

[slob]

In that case:
is your fuel filter blocked?
is there crud swilling round in the bottom of your fuel tank?
Plus as originally pointed out by Flip:
are both pump and tap diaphrams in good condition?
are there any cracks or splits in thevacuum hoses?

[Flip]

Could it be one (or more) of the pipes are being kinked when you run it with the tank up?

As an aside, I would be extra careful how you support the tank when you try it as if it’s too full it’ll stress the weld on the pivot and it’ll end up leaking.

[Darren69]

Still think its a clever design? I would say it's convoluted and unreliable.

[Jerryd]

As long as the vacuum tap is working as it should it might still be worth fitting a re-build kit to the pump if it’s never been changed- I did both on mine as I had vapour lock problems and didn’t want to revisit it to change something for the sake of a few quid.

Might be worth getting a JIS screwdriver if the vacuum pump’s not been apart for a while.

https://www.allensperformance.co.uk/shop/

Hi Why JIS screwdriver? I have taken the cover off already but not the other side as it seems well and truly frozen in place.

[Darren69]

'Cos a phillips one although looks like it fits, will knacker the heads. Same with the carb screws.

[Jerryd]

In that case:
is your fuel filter blocked?
is there crud swilling round in the bottom of your fuel tank?
Plus as originally pointed out by Flip:
are both pump and tap diaphrams in good condition?
are there any cracks or splits in thevacuum hoses?

Hi Had the tank out. Viniger over night. rinsed out and flushed through.
if i disconnet the main line that goes in the vacuum pump fuel thats fine.
the out of the pump seems to be as fault, nowt coming out, however yesterday it was good and really pumping.

[Jerryd]

'Cos a phillips one although looks like it fits, will knacker the heads. Same with the carb screws.

I found that out. 2 of them came out with grips.

[Flip]

You can usually identify JIS fixings by them having a little ‘punch mark’ on the heads.

[Darkness]

Differences between JIS and Phillips are explained here:

https://www.motorcycle.com/ask-mo-anything/difference-between-japanese-jis-phillips.html